wtf it works

Finish converting all callsites

Not too bad actually! Centralizing access into the helpers makes a big
difference.

go.mod

@@ -1,10 +1,8 @@
 module git.handmade.network/hmn/hmn
 
-go 1.16
+go 1.18
 
 require (
-	github.com/Masterminds/goutils v1.1.1 // indirect
-	github.com/Masterminds/semver v1.5.0 // indirect
 	github.com/Masterminds/sprig v2.22.0+incompatible
 	github.com/alecthomas/chroma v0.9.2
 	github.com/aws/aws-sdk-go-v2 v1.8.1
@@ -16,13 +14,10 @@ require (
 	github.com/go-stack/stack v1.8.0
 	github.com/google/uuid v1.2.0
 	github.com/gorilla/websocket v1.4.2
-	github.com/huandu/xstrings v1.3.2 // indirect
-	github.com/imdario/mergo v0.3.12 // indirect
 	github.com/jackc/pgconn v1.8.0
 	github.com/jackc/pgtype v1.6.2
 	github.com/jackc/pgx/v4 v4.10.1
 	github.com/jpillora/backoff v1.0.0
-	github.com/mitchellh/copystructure v1.1.1 // indirect
 	github.com/rs/zerolog v1.21.0
 	github.com/spf13/cobra v1.1.3
 	github.com/stretchr/testify v1.7.0
@@ -35,6 +30,39 @@ require (
 	golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d
 )
 
+require (
+	github.com/Masterminds/goutils v1.1.1 // indirect
+	github.com/Masterminds/semver v1.5.0 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.4.1 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/ini v1.2.1 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.2.2 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.2.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.5.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.3.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.6.2 // indirect
+	github.com/danwakefield/fnmatch v0.0.0-20160403171240-cbb64ac3d964 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dlclark/regexp2 v1.4.0 // indirect
+	github.com/huandu/xstrings v1.3.2 // indirect
+	github.com/imdario/mergo v0.3.12 // indirect
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/jackc/chunkreader/v2 v2.0.1 // indirect
+	github.com/jackc/pgio v1.0.0 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgproto3/v2 v2.0.6 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20200714003250-2b9c44734f2b // indirect
+	github.com/jackc/puddle v1.1.3 // indirect
+	github.com/mitchellh/copystructure v1.1.1 // indirect
+	github.com/mitchellh/reflectwalk v1.0.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 // indirect
+	golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4 // indirect
+	golang.org/x/text v0.3.6 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+)
+
 replace (
 	github.com/frustra/bbcode v0.0.0-20201127003707-6ef347fbe1c8 => github.com/HandmadeNetwork/bbcode v0.0.0-20210623031351-ec0e2e2e39d9
 	github.com/yuin/goldmark v1.4.1 => github.com/HandmadeNetwork/goldmark v1.4.1-0.20210707024600-f7e596e26b5e

go.sum

@@ -159,7 +159,6 @@ github.com/imdario/mergo v0.3.12 h1:b6R2BslTbIEToALKP7LxUvijTsNI9TAe80pLWN2g/HU=
 github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
-github.com/jackc/chunkreader v1.0.0 h1:4s39bBR8ByfqH+DKm8rQA3E1LHZWB9XWcrz8fqaZbe0=
 github.com/jackc/chunkreader v1.0.0/go.mod h1:RT6O25fNZIuasFJRyZ4R/Y2BbhasbmZXF9QQ7T3kePo=
 github.com/jackc/chunkreader/v2 v2.0.0/go.mod h1:odVSm741yZoC3dpHEUXIqA9tQRhFrgOHwnPIn9lDKlk=
 github.com/jackc/chunkreader/v2 v2.0.1 h1:i+RDz65UE+mmpjTfyz0MoVTnzeYxroil2G82ki7MGG8=
@@ -178,7 +177,6 @@ github.com/jackc/pgmock v0.0.0-20190831213851-13a1b77aafa2 h1:JVX6jT/XfzNqIjye47
 github.com/jackc/pgmock v0.0.0-20190831213851-13a1b77aafa2/go.mod h1:fGZlG77KXmcq05nJLRkk0+p82V8B8Dw8KN2/V9c/OAE=
 github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
 github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
-github.com/jackc/pgproto3 v1.1.0 h1:FYYE4yRw+AgI8wXIinMlNjBbp/UitDJwfj5LqqewP1A=
 github.com/jackc/pgproto3 v1.1.0/go.mod h1:eR5FA3leWg7p9aeAqi37XOTgTIbkABlvcPB3E5rlc78=
 github.com/jackc/pgproto3/v2 v2.0.0-alpha1.0.20190420180111-c116219b62db/go.mod h1:bhq50y+xrl9n5mRYyCBFKkpRVTLYJVWeCc+mEAI3yXA=
 github.com/jackc/pgproto3/v2 v2.0.0-alpha1.0.20190609003834-432c2951c711/go.mod h1:uH0AWtUmuShn0bcesswc4aBTWGvw0cAxIJp+6OB//Wg=

src/admintools/adminproject.go

@@ -55,7 +55,7 @@ func addCreateProjectCommand(projectCommand *cobra.Command) {
 			}
 			hmn := p.Project
 
-			newProjectID, err := db.QueryInt(ctx, tx,
+			newProjectID, err := db.QueryOneScalar[int](ctx, tx,
 				`
 				INSERT INTO handmade_project (
 					slug,

src/admintools/admintools.go

@@ -210,7 +210,7 @@ func init() {
 			}
 			defer tx.Rollback(ctx)
 
-			projectId, err := db.QueryInt(ctx, tx, `SELECT id FROM handmade_project WHERE slug = $1`, projectSlug)
+			projectId, err := db.QueryOneScalar[int](ctx, tx, `SELECT id FROM handmade_project WHERE slug = $1`, projectSlug)
 			if err != nil {
 				panic(err)
 			}
@@ -218,7 +218,7 @@ func init() {
 			var parentId *int
 			if parentSlug == "" {
 				// Select the root subforum
-				id, err := db.QueryInt(ctx, tx,
+				id, err := db.QueryOneScalar[int](ctx, tx,
 					`SELECT id FROM handmade_subforum WHERE parent_id IS NULL AND project_id = $1`,
 					projectId,
 				)
@@ -228,7 +228,7 @@ func init() {
 				parentId = &id
 			} else {
 				// Select the parent
-				id, err := db.QueryInt(ctx, tx,
+				id, err := db.QueryOneScalar[int](ctx, tx,
 					`SELECT id FROM handmade_subforum WHERE slug = $1 AND project_id = $2`,
 					parentSlug, projectId,
 				)
@@ -238,7 +238,7 @@ func init() {
 				parentId = &id
 			}
 
-			newId, err := db.QueryInt(ctx, tx,
+			newId, err := db.QueryOneScalar[int](ctx, tx,
 				`
 				INSERT INTO handmade_subforum (name, slug, blurb, parent_id, project_id)
 				VALUES ($1, $2, $3, $4, $5)
@@ -289,12 +289,12 @@ func init() {
 			}
 			defer tx.Rollback(ctx)
 
-			projectId, err := db.QueryInt(ctx, tx, `SELECT id FROM handmade_project WHERE slug = $1`, projectSlug)
+			projectId, err := db.QueryOneScalar[int](ctx, tx, `SELECT id FROM handmade_project WHERE slug = $1`, projectSlug)
 			if err != nil {
 				panic(err)
 			}
 
-			subforumId, err := db.QueryInt(ctx, tx,
+			subforumId, err := db.QueryOneScalar[int](ctx, tx,
 				`SELECT id FROM handmade_subforum WHERE slug = $1 AND project_id = $2`,
 				subforumSlug, projectId,
 			)

src/assets/assets.go

@@ -140,7 +140,7 @@ func Create(ctx context.Context, dbConn db.ConnOrTx, in CreateInput) (*models.As
 	}
 
 	// Fetch and return the new record
-	iasset, err := db.QueryOne(ctx, dbConn, models.Asset{},
+	asset, err := db.QueryOne[models.Asset](ctx, dbConn,
 		`
 		SELECT $columns
 		FROM handmade_asset
@@ -152,5 +152,5 @@ func Create(ctx context.Context, dbConn db.ConnOrTx, in CreateInput) (*models.As
 		return nil, oops.New(err, "failed to fetch newly-created asset")
 	}
 
-	return iasset.(*models.Asset), nil
+	return asset, nil
 }

src/auth/session.go

@@ -45,7 +45,7 @@ func makeCSRFToken() string {
 var ErrNoSession = errors.New("no session found")
 
 func GetSession(ctx context.Context, conn *pgxpool.Pool, id string) (*models.Session, error) {
-	row, err := db.QueryOne(ctx, conn, models.Session{}, "SELECT $columns FROM sessions WHERE id = $1", id)
+	sess, err := db.QueryOne[models.Session](ctx, conn, "SELECT $columns FROM sessions WHERE id = $1", id)
 	if err != nil {
 		if errors.Is(err, db.NotFound) {
 			return nil, ErrNoSession
@@ -53,7 +53,6 @@ func GetSession(ctx context.Context, conn *pgxpool.Pool, id string) (*models.Ses
 			return nil, oops.New(err, "failed to get session")
 		}
 	}
-	sess := row.(*models.Session)
 
 	return sess, nil
 }

src/db/db.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
+	"regexp"
 	"strings"
 
 	"git.handmade.network/hmn/hmn/src/config"
@@ -20,46 +21,17 @@ import (
 )
 
 /*
-Values of these kinds are ok to query even if they are not directly understood by pgtype.
-This is common for custom types like:
-
-	type ThreadType int
+A general error to be used when no results are found. This is the error returned
+by QueryOne, and can generally be used by other database helpers that fetch a single
+result but find nothing.
 */
-var queryableKinds = []reflect.Kind{
-	reflect.Int,
-}
-
-/*
-Checks if we are able to handle a particular type in a database query. This applies only to
-primitive types and not structs, since the database only returns individual primitive types
-and it is our job to stitch them back together into structs later.
-*/
-func typeIsQueryable(t reflect.Type) bool {
-	_, isRecognizedByPgtype := connInfo.DataTypeForValue(reflect.New(t).Elem().Interface()) // if pgtype recognizes it, we don't need to dig in further for more `db` tags
-	// NOTE: boy it would be nice if we didn't have to do reflect.New here, considering that pgtype is just doing reflection on the value anyway
-
-	if isRecognizedByPgtype {
-		return true
-	} else if t == reflect.TypeOf(uuid.UUID{}) {
-		return true
-	}
-
-	// pgtype doesn't recognize it, but maybe it's a primitive type we can deal with
-	k := t.Kind()
-	for _, qk := range queryableKinds {
-		if k == qk {
-			return true
-		}
-	}
-
-	return false
-}
+var NotFound = errors.New("not found")
 
 // This interface should match both a direct pgx connection or a pgx transaction.
 type ConnOrTx interface {
-	Query(ctx context.Context, sql string, args ...interface{}) (pgx.Rows, error)
-	QueryRow(ctx context.Context, sql string, args ...interface{}) pgx.Row
-	Exec(ctx context.Context, sql string, args ...interface{}) (pgconn.CommandTag, error)
+	Query(ctx context.Context, sql string, args ...any) (pgx.Rows, error)
+	QueryRow(ctx context.Context, sql string, args ...any) pgx.Row
+	Exec(ctx context.Context, sql string, args ...any) (pgconn.CommandTag, error)
 
 	// Both raw database connections and transactions in pgx can begin/commit
 	// transactions. For database connections it does the obvious thing; for
@@ -70,6 +42,8 @@ type ConnOrTx interface {
 
 var connInfo = pgtype.NewConnInfo()
 
+// Creates a new connection to the HMN database.
+// This connection is not safe for concurrent use.
 func NewConn() *pgx.Conn {
 	conn, err := pgx.Connect(context.Background(), config.Config.Postgres.DSN())
 	if err != nil {
@@ -79,6 +53,8 @@ func NewConn() *pgx.Conn {
 	return conn
 }
 
+// Creates a connection pool for the HMN database.
+// The resulting pool is safe for concurrent use.
 func NewConnPool(minConns, maxConns int32) *pgxpool.Pool {
 	cfg, err := pgxpool.ParseConfig(config.Config.Postgres.DSN())
 
@@ -95,144 +71,20 @@ func NewConnPool(minConns, maxConns int32) *pgxpool.Pool {
 	return conn
 }
 
-type StructQueryIterator struct {
-	fieldPaths [][]int
-	rows       pgx.Rows
-	destType   reflect.Type
-	closed     chan struct{}
-}
+/*
+Performs a SQL query and returns a slice of all the result rows. The query is just plain SQL, but make sure to read the package documentation for details. You must explicitly provide the type argument - this is how it knows what Go type to map the results to, and it cannot be inferred.
 
-func (it *StructQueryIterator) Next() (interface{}, bool) {
-	hasNext := it.rows.Next()
-	if !hasNext {
-		it.Close()
-		return nil, false
-	}
+Any SQL query may be performed, including INSERT and UPDATE - as long as it returns a result set, you can use this. If the query does not return a result set, or you simply do not care about the result set, call Exec directly on your pgx connection.
 
-	result := reflect.New(it.destType)
-
-	vals, err := it.rows.Values()
-	if err != nil {
-		panic(err)
-	}
-
-	// Better logging of panics in this confusing reflection process
-	var currentField reflect.StructField
-	var currentValue reflect.Value
-	var currentIdx int
-	defer func() {
-		if r := recover(); r != nil {
-			if currentValue.IsValid() {
-				logging.Error().
-					Int("index", currentIdx).
-					Str("field name", currentField.Name).
-					Stringer("field type", currentField.Type).
-					Interface("value", currentValue.Interface()).
-					Stringer("value type", currentValue.Type()).
-					Msg("panic in iterator")
-			}
-
-			if currentField.Name != "" {
-				panic(fmt.Errorf("panic while processing field '%s': %v", currentField.Name, r))
-			} else {
-				panic(r)
-			}
-		}
-	}()
-
-	for i, val := range vals {
-		currentIdx = i
-		if val == nil {
-			continue
-		}
-
-		var field reflect.Value
-		field, currentField = followPathThroughStructs(result, it.fieldPaths[i])
-		if field.Kind() == reflect.Ptr {
-			field.Set(reflect.New(field.Type().Elem()))
-			field = field.Elem()
-		}
-
-		// Some actual values still come through as pointers (like net.IPNet). Dunno why.
-		// Regardless, we know it's not nil, so we can get at the contents.
-		valReflected := reflect.ValueOf(val)
-		if valReflected.Kind() == reflect.Ptr {
-			valReflected = valReflected.Elem()
-		}
-		currentValue = valReflected
-
-		switch field.Kind() {
-		case reflect.Int:
-			field.SetInt(valReflected.Int())
-		default:
-			field.Set(valReflected)
-		}
-
-		currentField = reflect.StructField{}
-		currentValue = reflect.Value{}
-	}
-
-	return result.Interface(), true
-}
-
-func (it *StructQueryIterator) Close() {
-	it.rows.Close()
-	select {
-	case it.closed <- struct{}{}:
-	default:
-	}
-}
-
-func (it *StructQueryIterator) ToSlice() []interface{} {
-	defer it.Close()
-	var result []interface{}
-	for {
-		row, ok := it.Next()
-		if !ok {
-			err := it.rows.Err()
-			if err != nil {
-				panic(oops.New(err, "error while iterating through db results"))
-			}
-			break
-		}
-		result = append(result, row)
-	}
-	return result
-}
-
-func followPathThroughStructs(structPtrVal reflect.Value, path []int) (reflect.Value, reflect.StructField) {
-	if len(path) < 1 {
-		panic(oops.New(nil, "can't follow an empty path"))
-	}
-
-	if structPtrVal.Kind() != reflect.Ptr || structPtrVal.Elem().Kind() != reflect.Struct {
-		panic(oops.New(nil, "structPtrVal must be a pointer to a struct; got value of type %s", structPtrVal.Type()))
-	}
-
-	// more informative panic recovery
-	var field reflect.StructField
-	defer func() {
-		if r := recover(); r != nil {
-			panic(oops.New(nil, "panic at field '%s': %v", field.Name, r))
-		}
-	}()
-
-	val := structPtrVal
-	for _, i := range path {
-		if val.Kind() == reflect.Ptr && val.Type().Elem().Kind() == reflect.Struct {
-			if val.IsNil() {
-				val.Set(reflect.New(val.Type().Elem()))
-			}
-			val = val.Elem()
-		}
-		field = val.Type().Field(i)
-		val = val.Field(i)
-	}
-	return val, field
-}
-
-func Query(ctx context.Context, conn ConnOrTx, destExample interface{}, query string, args ...interface{}) ([]interface{}, error) {
-	it, err := QueryIterator(ctx, conn, destExample, query, args...)
+This function always returns pointers to the values. This is convenient for structs, but for other types, you may wish to use QueryScalar.
+*/
+func Query[T any](
+	ctx context.Context,
+	conn ConnOrTx,
+	query string,
+	args ...any,
+) ([]*T, error) {
+	it, err := QueryIterator[T](ctx, conn, query, args...)
 	if err != nil {
 		return nil, err
 	} else {
@@ -240,27 +92,99 @@ func Query(ctx context.Context, conn ConnOrTx, destExample interface{}, query st
 	}
 }
 
-func QueryIterator(ctx context.Context, conn ConnOrTx, destExample interface{}, query string, args ...interface{}) (*StructQueryIterator, error) {
-	destType := reflect.TypeOf(destExample)
-	columnNames, fieldPaths, err := getColumnNamesAndPaths(destType, nil, nil)
+/*
+Identical to Query, but returns only the first result row. If there are no
+rows in the result set, returns NotFound.
+*/
+func QueryOne[T any](
+	ctx context.Context,
+	conn ConnOrTx,
+	query string,
+	args ...any,
+) (*T, error) {
+	rows, err := QueryIterator[T](ctx, conn, query, args...)
 	if err != nil {
-		return nil, oops.New(err, "failed to generate column names")
+		return nil, err
+	}
+	defer rows.Close()
+
+	result, hasRow := rows.Next()
+	if !hasRow {
+		return nil, NotFound
 	}
 
-	columns := make([]string, 0, len(columnNames))
-	for _, strSlice := range columnNames {
-		tableName := strings.Join(strSlice[0:len(strSlice)-1], "_")
-		fullName := strSlice[len(strSlice)-1]
-		if tableName != "" {
-			fullName = tableName + "." + fullName
-		}
-		columns = append(columns, fullName)
+	return result, nil
 }
 
-	columnNamesString := strings.Join(columns, ", ")
-	query = strings.Replace(query, "$columns", columnNamesString, -1)
+/*
+Identical to Query, but returns concrete values instead of pointers. More convenient
+for primitive types.
+*/
+func QueryScalar[T any](
+	ctx context.Context,
+	conn ConnOrTx,
+	query string,
+	args ...any,
+) ([]T, error) {
+	rows, err := QueryIterator[T](ctx, conn, query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
 
-	rows, err := conn.Query(ctx, query, args...)
+	var result []T
+	for {
+		val, hasRow := rows.Next()
+		if !hasRow {
+			break
+		}
+		result = append(result, *val)
+	}
+
+	return result, nil
+}
+
+/*
+Identical to QueryScalar, but returns only the first result value. If there are
+no rows in the result set, returns NotFound.
+*/
+func QueryOneScalar[T any](
+	ctx context.Context,
+	conn ConnOrTx,
+	query string,
+	args ...any,
+) (T, error) {
+	rows, err := QueryIterator[T](ctx, conn, query, args...)
+	if err != nil {
+		var zero T
+		return zero, err
+	}
+	defer rows.Close()
+
+	result, hasRow := rows.Next()
+	if !hasRow {
+		var zero T
+		return zero, NotFound
+	}
+
+	return *result, nil
+}
+
+/*
+Identical to Query, but returns the ResultIterator instead of automatically converting the results to a slice. The iterator must be closed after use.
+*/
+func QueryIterator[T any](
+	ctx context.Context,
+	conn ConnOrTx,
+	query string,
+	args ...any,
+) (*Iterator[T], error) {
+	var destExample T
+	destType := reflect.TypeOf(destExample)
+
+	compiled := compileQuery(query, destType)
+
+	rows, err := conn.Query(ctx, compiled.query, args...)
 	if err != nil {
 		if errors.Is(err, context.DeadlineExceeded) {
 			panic("query exceeded its deadline")
@@ -268,10 +192,11 @@ func QueryIterator(ctx context.Context, conn ConnOrTx, destExample interface{},
 		return nil, err
 	}
 
-	it := &StructQueryIterator{
-		fieldPaths: fieldPaths,
+	it := &Iterator[T]{
+		fieldPaths:       compiled.fieldPaths,
 		rows:             rows,
-		destType:   destType,
+		destType:         compiled.destType,
+		destTypeIsScalar: typeIsQueryable(compiled.destType),
 		closed:           make(chan struct{}, 1),
 	}
 
@@ -292,16 +217,72 @@ func QueryIterator(ctx context.Context, conn ConnOrTx, destExample interface{},
 	return it, nil
 }
 
-func getColumnNamesAndPaths(destType reflect.Type, pathSoFar []int, prefix []string) (names [][]string, paths [][]int, err error) {
-	var columnNames [][]string
-	var fieldPaths [][]int
+// TODO: QueryFunc?
+
+type compiledQuery struct {
+	query      string
+	destType   reflect.Type
+	fieldPaths []fieldPath
+}
+
+var reColumnsPlaceholder = regexp.MustCompile(`\$columns({(.*?)})?`)
+
+func compileQuery(query string, destType reflect.Type) compiledQuery {
+	columnsMatch := reColumnsPlaceholder.FindStringSubmatch(query)
+	hasColumnsPlaceholder := columnsMatch != nil
+
+	if hasColumnsPlaceholder {
+		// The presence of the $columns placeholder means that the destination type
+		// must be a struct, and we will plonk that struct's fields into the query.
+
+		if destType.Kind() != reflect.Struct {
+			panic("$columns can only be used when querying into a struct")
+		}
+
+		var prefix []string
+		prefixText := columnsMatch[2]
+		if prefixText != "" {
+			prefix = []string{prefixText}
+		}
+
+		columnNames, fieldPaths := getColumnNamesAndPaths(destType, nil, prefix)
+
+		columns := make([]string, 0, len(columnNames))
+		for _, strSlice := range columnNames {
+			tableName := strings.Join(strSlice[0:len(strSlice)-1], "_")
+			fullName := strSlice[len(strSlice)-1]
+			if tableName != "" {
+				fullName = tableName + "." + fullName
+			}
+			columns = append(columns, fullName)
+		}
+
+		columnNamesString := strings.Join(columns, ", ")
+		query = reColumnsPlaceholder.ReplaceAllString(query, columnNamesString)
+
+		return compiledQuery{
+			query:      query,
+			destType:   destType,
+			fieldPaths: fieldPaths,
+		}
+	} else {
+		return compiledQuery{
+			query:    query,
+			destType: destType,
+		}
+	}
+}
+
+func getColumnNamesAndPaths(destType reflect.Type, pathSoFar []int, prefix []string) (names []columnName, paths []fieldPath) {
+	var columnNames []columnName
+	var fieldPaths []fieldPath
 
 	if destType.Kind() == reflect.Ptr {
 		destType = destType.Elem()
 	}
 
 	if destType.Kind() != reflect.Struct {
-		return nil, nil, oops.New(nil, "can only get column names and paths from a struct, got type '%v' (at prefix '%v')", destType.Name(), prefix)
+		panic(fmt.Errorf("can only get column names and paths from a struct, got type '%v' (at prefix '%v')", destType.Name(), prefix))
 	}
 
 	type AnonPrefix struct {
@@ -348,108 +329,214 @@ func getColumnNamesAndPaths(destType reflect.Type, pathSoFar []int, prefix []str
 				columnNames = append(columnNames, fieldColumnNames)
 				fieldPaths = append(fieldPaths, path)
 			} else if fieldType.Kind() == reflect.Struct {
-				subCols, subPaths, err := getColumnNamesAndPaths(fieldType, path, fieldColumnNames)
-				if err != nil {
-					return nil, nil, err
-				}
+				subCols, subPaths := getColumnNamesAndPaths(fieldType, path, fieldColumnNames)
 				columnNames = append(columnNames, subCols...)
 				fieldPaths = append(fieldPaths, subPaths...)
 			} else {
-				return nil, nil, oops.New(nil, "field '%s' in type %s has invalid type '%s'", field.Name, destType, field.Type)
+				panic(fmt.Errorf("field '%s' in type %s has invalid type '%s'", field.Name, destType, field.Type))
 			}
 		}
 	}
 
-	return columnNames, fieldPaths, nil
+	return columnNames, fieldPaths
 }
 
 /*
-A general error to be used when no results are found. This is the error returned
-by QueryOne, and can generally be used by other database helpers that fetch a single
-result but find nothing.
+Values of these kinds are ok to query even if they are not directly understood by pgtype.
+This is common for custom types like:
+
+	type ThreadType int
 */
-var NotFound = errors.New("not found")
-
-func QueryOne(ctx context.Context, conn ConnOrTx, destExample interface{}, query string, args ...interface{}) (interface{}, error) {
-	rows, err := QueryIterator(ctx, conn, destExample, query, args...)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	result, hasRow := rows.Next()
-	if !hasRow {
-		return nil, NotFound
+var queryableKinds = []reflect.Kind{
+	reflect.Int,
 }
 
-	return result, nil
+/*
+Checks if we are able to handle a particular type in a database query. This applies only to
+primitive types and not structs, since the database only returns individual primitive types
+and it is our job to stitch them back together into structs later.
+*/
+func typeIsQueryable(t reflect.Type) bool {
+	_, isRecognizedByPgtype := connInfo.DataTypeForValue(reflect.New(t).Elem().Interface()) // if pgtype recognizes it, we don't need to dig in further for more `db` tags
+	// NOTE: boy it would be nice if we didn't have to do reflect.New here, considering that pgtype is just doing reflection on the value anyway
+
+	if isRecognizedByPgtype {
+		return true
+	} else if t == reflect.TypeOf(uuid.UUID{}) {
+		return true
 	}
 
-func QueryScalar(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (interface{}, error) {
-	rows, err := conn.Query(ctx, query, args...)
-	if err != nil {
-		return nil, err
+	// pgtype doesn't recognize it, but maybe it's a primitive type we can deal with
+	k := t.Kind()
+	for _, qk := range queryableKinds {
+		if k == qk {
+			return true
+		}
 	}
-	defer rows.Close()
 
-	if rows.Next() {
-		vals, err := rows.Values()
+	return false
+}
+
+type columnName []string
+
+// A path to a particular field in query's destination type. Each index in the slice
+// corresponds to a field index for use with Field on a reflect.Type or reflect.Value.
+type fieldPath []int
+
+type Iterator[T any] struct {
+	fieldPaths       []fieldPath
+	rows             pgx.Rows
+	destType         reflect.Type
+	destTypeIsScalar bool // NOTE(ben): Make sure this gets set every time destType gets set, based on typeIsQueryable(destType). This is kinda fragile...but also contained to this file, so doesn't seem worth a lazy evaluation or a constructor function.
+	closed           chan struct{}
+}
+
+func (it *Iterator[T]) Next() (*T, bool) {
+	// TODO(ben): What happens if this panics? Does it leak resources? Do we need
+	// to put a recover() here and close the rows?
+
+	hasNext := it.rows.Next()
+	if !hasNext {
+		it.Close()
+		return nil, false
+	}
+
+	result := reflect.New(it.destType)
+
+	vals, err := it.rows.Values()
 	if err != nil {
 		panic(err)
 	}
 
+	if it.destTypeIsScalar {
+		// This type can be directly queried, meaning pgx recognizes it, it's
+		// a simple scalar thing, and we can just take the easy way out.
 		if len(vals) != 1 {
-			return nil, oops.New(nil, "you must query exactly one field with QueryScalar, not %v", len(vals))
+			panic(fmt.Errorf("tried to query a scalar value, but got %v values in the row", len(vals)))
+		}
+		setValueFromDB(result.Elem(), reflect.ValueOf(vals[0]))
+		return result.Interface().(*T), true
+	} else {
+		var currentField reflect.StructField
+		var currentValue reflect.Value
+		var currentIdx int
+
+		// Better logging of panics in this confusing reflection process
+		defer func() {
+			if r := recover(); r != nil {
+				if currentValue.IsValid() {
+					logging.Error().
+						Int("index", currentIdx).
+						Str("field name", currentField.Name).
+						Stringer("field type", currentField.Type).
+						Interface("value", currentValue.Interface()).
+						Stringer("value type", currentValue.Type()).
+						Msg("panic in iterator")
 				}
 
-		return vals[0], nil
+				if currentField.Name != "" {
+					panic(fmt.Errorf("panic while processing field '%s': %v", currentField.Name, r))
+				} else {
+					panic(r)
+				}
+			}
+		}()
+
+		for i, val := range vals {
+			currentIdx = i
+			if val == nil {
+				continue
 			}
 
-	return nil, NotFound
+			var field reflect.Value
+			field, currentField = followPathThroughStructs(result, it.fieldPaths[i])
+			if field.Kind() == reflect.Ptr {
+				field.Set(reflect.New(field.Type().Elem()))
+				field = field.Elem()
 			}
 
-func QueryString(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (string, error) {
-	result, err := QueryScalar(ctx, conn, query, args...)
-	if err != nil {
-		return "", err
+			// Some actual values still come through as pointers (like net.IPNet). Dunno why.
+			// Regardless, we know it's not nil, so we can get at the contents.
+			valReflected := reflect.ValueOf(val)
+			if valReflected.Kind() == reflect.Ptr {
+				valReflected = valReflected.Elem()
+			}
+			currentValue = valReflected
+
+			setValueFromDB(field, valReflected)
+
+			currentField = reflect.StructField{}
+			currentValue = reflect.Value{}
 		}
 
-	switch r := result.(type) {
-	case string:
-		return r, nil
+		return result.Interface().(*T), true
+	}
+}
+
+func setValueFromDB(dest reflect.Value, value reflect.Value) {
+	switch dest.Kind() {
+	case reflect.Int:
+		dest.SetInt(value.Int())
 	default:
-		return "", oops.New(nil, "QueryString got a non-string result: %v", result)
+		dest.Set(value)
 	}
 }
 
-func QueryInt(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (int, error) {
-	result, err := QueryScalar(ctx, conn, query, args...)
-	if err != nil {
-		return 0, err
-	}
-
-	switch r := result.(type) {
-	case int:
-		return r, nil
-	case int32:
-		return int(r), nil
-	case int64:
-		return int(r), nil
+func (it *Iterator[any]) Close() {
+	it.rows.Close()
+	select {
+	case it.closed <- struct{}{}:
 	default:
-		return 0, oops.New(nil, "QueryInt got a non-int result: %v", result)
 	}
 }
 
-func QueryBool(ctx context.Context, conn ConnOrTx, query string, args ...interface{}) (bool, error) {
-	result, err := QueryScalar(ctx, conn, query, args...)
+/*
+Pulls all the remaining values into a slice, and closes the iterator.
+*/
+func (it *Iterator[T]) ToSlice() []*T {
+	defer it.Close()
+	var result []*T
+	for {
+		row, ok := it.Next()
+		if !ok {
+			err := it.rows.Err()
 			if err != nil {
-		return false, err
+				panic(oops.New(err, "error while iterating through db results"))
+			}
+			break
+		}
+		result = append(result, row)
+	}
+	return result
 }
 
-	switch r := result.(type) {
-	case bool:
-		return r, nil
-	default:
-		return false, oops.New(nil, "QueryBool got a non-bool result: %v", result)
+func followPathThroughStructs(structPtrVal reflect.Value, path []int) (reflect.Value, reflect.StructField) {
+	if len(path) < 1 {
+		panic(oops.New(nil, "can't follow an empty path"))
 	}
+
+	if structPtrVal.Kind() != reflect.Ptr || structPtrVal.Elem().Kind() != reflect.Struct {
+		panic(oops.New(nil, "structPtrVal must be a pointer to a struct; got value of type %s", structPtrVal.Type()))
+	}
+
+	// more informative panic recovery
+	var field reflect.StructField
+	defer func() {
+		if r := recover(); r != nil {
+			panic(oops.New(nil, "panic at field '%s': %v", field.Name, r))
+		}
+	}()
+
+	val := structPtrVal
+	for _, i := range path {
+		if val.Kind() == reflect.Ptr && val.Type().Elem().Kind() == reflect.Struct {
+			if val.IsNil() {
+				val.Set(reflect.New(val.Type().Elem()))
+			}
+			val = val.Elem()
+		}
+		field = val.Type().Field(i)
+		val = val.Field(i)
+	}
+	return val, field
 }

src/db/db_test.go

@@ -10,13 +10,90 @@ import (
 
 func TestPaths(t *testing.T) {
 	type CustomInt int
+	type S2 struct {
+		B  bool  `db:"B"`  // field 0
+		PB *bool `db:"PB"` // field 1
+
+		NoTag string // field 2
+	}
+	type S struct {
+		I   int        `db:"I"`   // field 0
+		PI  *int       `db:"PI"`  // field 1
+		CI  CustomInt  `db:"CI"`  // field 2
+		PCI *CustomInt `db:"PCI"` // field 3
+		S2  `db:"S2"`  // field 4 (embedded!)
+		PS2 *S2        `db:"PS2"` // field 5
+
+		NoTag int // field 6
+	}
+	type Nested struct {
+		S  S  `db:"S"`  // field 0
+		PS *S `db:"PS"` // field 1
+
+		NoTag S // field 2
+	}
+	type Embedded struct {
+		NoTag  S // field 0
+		Nested   // field 1
+	}
+
+	names, paths := getColumnNamesAndPaths(reflect.TypeOf(Embedded{}), nil, nil)
+	assert.Equal(t, []columnName{
+		{"S", "I"}, {"S", "PI"},
+		{"S", "CI"}, {"S", "PCI"},
+		{"S", "S2", "B"}, {"S", "S2", "PB"},
+		{"S", "PS2", "B"}, {"S", "PS2", "PB"},
+		{"PS", "I"}, {"PS", "PI"},
+		{"PS", "CI"}, {"PS", "PCI"},
+		{"PS", "S2", "B"}, {"PS", "S2", "PB"},
+		{"PS", "PS2", "B"}, {"PS", "PS2", "PB"},
+	}, names)
+	assert.Equal(t, []fieldPath{
+		{1, 0, 0}, {1, 0, 1}, // Nested.S.I, Nested.S.PI
+		{1, 0, 2}, {1, 0, 3}, // Nested.S.CI, Nested.S.PCI
+		{1, 0, 4, 0}, {1, 0, 4, 1}, // Nested.S.S2.B, Nested.S.S2.PB
+		{1, 0, 5, 0}, {1, 0, 5, 1}, // Nested.S.PS2.B, Nested.S.PS2.PB
+		{1, 1, 0}, {1, 1, 1}, // Nested.PS.I, Nested.PS.PI
+		{1, 1, 2}, {1, 1, 3}, // Nested.PS.CI, Nested.PS.PCI
+		{1, 1, 4, 0}, {1, 1, 4, 1}, // Nested.PS.S2.B, Nested.PS.S2.PB
+		{1, 1, 5, 0}, {1, 1, 5, 1}, // Nested.PS.PS2.B, Nested.PS.PS2.PB
+	}, paths)
+	assert.True(t, len(names) == len(paths))
+
+	testStruct := Embedded{}
+	for i, path := range paths {
+		val, field := followPathThroughStructs(reflect.ValueOf(&testStruct), path)
+		assert.True(t, val.IsValid())
+		assert.True(t, strings.Contains(names[i][len(names[i])-1], field.Name))
+	}
+}
+
+func TestCompileQuery(t *testing.T) {
+	t.Run("simple struct", func(t *testing.T) {
+		type Dest struct {
+			Foo  int    `db:"foo"`
+			Bar  bool   `db:"bar"`
+			Nope string // no tag
+		}
+
+		compiled := compileQuery("SELECT $columns FROM greeblies", reflect.TypeOf(Dest{}))
+		assert.Equal(t, "SELECT foo, bar FROM greeblies", compiled.query)
+	})
+	t.Run("complex structs", func(t *testing.T) {
+		type CustomInt int
+		type S2 struct {
+			B  bool  `db:"B"`
+			PB *bool `db:"PB"`
+
+			NoTag string
+		}
 		type S struct {
 			I   int        `db:"I"`
 			PI  *int       `db:"PI"`
 			CI  CustomInt  `db:"CI"`
 			PCI *CustomInt `db:"PCI"`
-		B   bool       `db:"B"`
-		PB  *bool      `db:"PB"`
+			S2  `db:"S2"`  // embedded!
+			PS2 *S2        `db:"PS2"`
 
 			NoTag int
 		}
@@ -26,34 +103,48 @@ func TestPaths(t *testing.T) {
 
 			NoTag S
 		}
-	type Embedded struct {
+		type Dest struct {
 			NoTag S
 			Nested
 		}
 
-	names, paths, err := getColumnNamesAndPaths(reflect.TypeOf(Embedded{}), nil, "")
-	if assert.Nil(t, err) {
-		assert.Equal(t, []string{
-			"S.I", "S.PI",
-			"S.CI", "S.PCI",
-			"S.B", "S.PB",
-			"PS.I", "PS.PI",
-			"PS.CI", "PS.PCI",
-			"PS.B", "PS.PB",
-		}, names)
-		assert.Equal(t, [][]int{
-			{1, 0, 0}, {1, 0, 1}, {1, 0, 2}, {1, 0, 3}, {1, 0, 4}, {1, 0, 5},
-			{1, 1, 0}, {1, 1, 1}, {1, 1, 2}, {1, 1, 3}, {1, 1, 4}, {1, 1, 5},
-		}, paths)
-		assert.True(t, len(names) == len(paths))
+		compiled := compileQuery("SELECT $columns FROM greeblies", reflect.TypeOf(Dest{}))
+		assert.Equal(t, "SELECT S.I, S.PI, S.CI, S.PCI, S_S2.B, S_S2.PB, S_PS2.B, S_PS2.PB, PS.I, PS.PI, PS.CI, PS.PCI, PS_S2.B, PS_S2.PB, PS_PS2.B, PS_PS2.PB FROM greeblies", compiled.query)
+	})
+	t.Run("int", func(t *testing.T) {
+		type Dest int
+
+		// There should be no error here because we do not need to extract columns from
+		// the destination type. There may be errors down the line in value iteration, but
+		// that is always the case if the Go types don't match the query.
+		compiled := compileQuery("SELECT id FROM greeblies", reflect.TypeOf(Dest(0)))
+		assert.Equal(t, "SELECT id FROM greeblies", compiled.query)
+	})
+	t.Run("just one table", func(t *testing.T) {
+		type Dest struct {
+			Foo  int    `db:"foo"`
+			Bar  bool   `db:"bar"`
+			Nope string // no tag
 		}
 
-	testStruct := Embedded{}
-	for i, path := range paths {
-		val, field := followPathThroughStructs(reflect.ValueOf(&testStruct), path)
-		assert.True(t, val.IsValid())
-		assert.True(t, strings.Contains(names[i], field.Name))
-	}
+		// The prefix is necessary because otherwise we would have to provide a struct with
+		// a db tag in order to provide the query with the `greeblies.` prefix in the
+		// final query. This comes up a lot when we do a JOIN to help with a condition, but
+		// don't actually care about any of the data we joined to.
+		compiled := compileQuery(
+			"SELECT $columns{greeblies} FROM greeblies NATURAL JOIN props",
+			reflect.TypeOf(Dest{}),
+		)
+		assert.Equal(t, "SELECT greeblies.foo, greeblies.bar FROM greeblies NATURAL JOIN props", compiled.query)
+	})
+
+	t.Run("using $columns without a struct is not allowed", func(t *testing.T) {
+		type Dest int
+
+		assert.Panics(t, func() {
+			compileQuery("SELECT $columns FROM greeblies", reflect.TypeOf(Dest(0)))
+		})
+	})
 }
 
 func TestQueryBuilder(t *testing.T) {

src/db/doc.go

@@ -0,0 +1,59 @@
+/*
+This package contains lowish-level APIs for making database queries to our Postgres database. It streamlines the process of mapping query results to Go types, while allowing you to write arbitrary SQL queries.
+
+The primary functions are Query and QueryIterator. See the package and function examples for detailed usage.
+
+Query syntax
+
+This package allows a few small extensions to SQL syntax to streamline the interaction between Go and Postgres.
+
+Arguments can be provided using placeholders like $1, $2, etc. All arguments will be safely escaped and mapped from their Go type to the correct Postgres type. (This is a direct proxy to pgx.)
+
+	projectIDs, err := db.Query[int](ctx, conn,
+		`
+		SELECT id
+		FROM handmade_project
+		WHERE
+			slug = ANY($1)
+			AND hidden = $2
+		`,
+		[]string{"4coder", "metadesk"},
+		false,
+	)
+
+(This also demonstrates a useful tip: if you want to use a slice in your query, use Postgres arrays instead of IN.)
+
+When querying individual fields, you can simply select the field like so:
+
+	ids, err := db.Query[int](ctx, conn, `SELECT id FROM handmade_project`)
+
+To query multiple columns at once, you may use a struct type with `db:"column_name"` tags, and the special $columns placeholder:
+
+	type Project struct {
+		ID          int       `db:"id"`
+		Slug        string    `db:"slug"`
+		DateCreated time.Time `db:"date_created"`
+	}
+	projects, err := db.Query[Project](ctx, conn, `SELECT $columns FROM ...`)
+	// Resulting query:
+	// SELECT id, slug, date_created FROM ...
+
+Sometimes a table name prefix is required on each column to disambiguate between column names, especially when performing a JOIN. In those situations, you can include the prefix in the $columns placeholder like $columns{prefix}:
+
+	type Project struct {
+		ID          int       `db:"id"`
+		Slug        string    `db:"slug"`
+		DateCreated time.Time `db:"date_created"`
+	}
+	orphanedProjects, err := db.Query[Project](ctx, conn, `
+		SELECT $columns{projects}
+		FROM
+			handmade_project AS projects
+			LEFT JOIN handmade_user_projects AS uproj
+		WHERE
+			uproj.user_id IS NULL
+	`)
+	// Resulting query:
+	// SELECT projects.id, projects.slug, projects.date_created FROM ...
+*/
+package db

src/db/query_builder.go

@@ -7,7 +7,7 @@ import (
 
 type QueryBuilder struct {
 	sql  strings.Builder
-	args []interface{}
+	args []any
 }
 
 /*
@@ -18,7 +18,7 @@ of `$?` will be replaced with the correct argument number.
 	foo ARG1 bar ARG2 baz $?
 	foo ARG1 bar ARG2 baz ARG3
 */
-func (qb *QueryBuilder) Add(sql string, args ...interface{}) {
+func (qb *QueryBuilder) Add(sql string, args ...any) {
 	numPlaceholders := strings.Count(sql, "$?")
 	if numPlaceholders != len(args) {
 		panic(fmt.Errorf("cannot add chunk to query; expected %d arguments but got %d", numPlaceholders, len(args)))
@@ -37,6 +37,6 @@ func (qb *QueryBuilder) String() string {
 	return qb.sql.String()
 }
 
-func (qb *QueryBuilder) Args() []interface{} {
+func (qb *QueryBuilder) Args() []any {
 	return qb.args
 }

src/discord/commands.go

@@ -90,12 +90,9 @@ func (bot *botInstance) handleProfileCommand(ctx context.Context, i *Interaction
 		return
 	}
 
-	type profileResult struct {
-		HMNUser models.User `db:"auth_user"`
-	}
-	ires, err := db.QueryOne(ctx, bot.dbConn, profileResult{},
+	hmnUser, err := db.QueryOne[models.User](ctx, bot.dbConn,
 		`
-		SELECT $columns
+		SELECT $columns{auth_user}
 		FROM
 			handmade_discorduser AS duser
 			JOIN auth_user ON duser.hmn_user_id = auth_user.id
@@ -122,16 +119,15 @@ func (bot *botInstance) handleProfileCommand(ctx context.Context, i *Interaction
 		}
 		return
 	}
-	res := ires.(*profileResult)
 
 	projectsAndStuff, err := hmndata.FetchProjects(ctx, bot.dbConn, nil, hmndata.ProjectsQuery{
-		OwnerIDs: []int{res.HMNUser.ID},
+		OwnerIDs: []int{hmnUser.ID},
 	})
 	if err != nil {
 		logging.ExtractLogger(ctx).Error().Err(err).Msg("failed to fetch user projects")
 	}
 
-	url := hmnurl.BuildUserProfile(res.HMNUser.Username)
+	url := hmnurl.BuildUserProfile(hmnUser.Username)
 	msg := fmt.Sprintf("<@%s>'s profile can be viewed at %s.", member.User.ID, url)
 	if len(projectsAndStuff) > 0 {
 		projectNoun := "projects"

src/discord/gateway.go

@@ -250,7 +250,7 @@ func (bot *botInstance) connect(ctx context.Context) error {
 	// an old one or starting a new one.
 
 	shouldResume := true
-	isession, err := db.QueryOne(ctx, bot.dbConn, models.DiscordSession{}, `SELECT $columns FROM discord_session`)
+	session, err := db.QueryOne[models.DiscordSession](ctx, bot.dbConn, `SELECT $columns FROM discord_session`)
 	if err != nil {
 		if errors.Is(err, db.NotFound) {
 			// No session yet! Just identify and get on with it
@@ -262,8 +262,6 @@ func (bot *botInstance) connect(ctx context.Context) error {
 
 	if shouldResume {
 		// Reconnect to the previous session
-		session := isession.(*models.DiscordSession)
-
 		err := bot.sendGatewayMessage(ctx, GatewayMessage{
 			Opcode: OpcodeResume,
 			Data: Resume{
@@ -356,7 +354,7 @@ func (bot *botInstance) doSender(ctx context.Context) {
 		}
 		bot.didAckHeartbeat = false
 
-		latestSequenceNumber, err := db.QueryInt(ctx, bot.dbConn, `SELECT sequence_number FROM discord_session`)
+		latestSequenceNumber, err := db.QueryOneScalar[int](ctx, bot.dbConn, `SELECT sequence_number FROM discord_session`)
 		if err != nil {
 			log.Error().Err(err).Msg("failed to fetch latest sequence number from the db")
 			return false
@@ -408,7 +406,7 @@ func (bot *botInstance) doSender(ctx context.Context) {
 				}
 				defer tx.Rollback(ctx)
 
-				msgs, err := db.Query(ctx, tx, models.DiscordOutgoingMessage{}, `
+				msgs, err := db.Query[models.DiscordOutgoingMessage](ctx, tx, `
 					SELECT $columns
 					FROM discord_outgoingmessages
 					ORDER BY id ASC
@@ -418,8 +416,7 @@ func (bot *botInstance) doSender(ctx context.Context) {
 					return
 				}
 
-				for _, imsg := range msgs {
-					msg := imsg.(*models.DiscordOutgoingMessage)
+				for _, msg := range msgs {
 					if time.Now().After(msg.ExpiresAt) {
 						continue
 					}

src/discord/history.go

@@ -73,12 +73,9 @@ func RunHistoryWatcher(ctx context.Context, dbConn *pgxpool.Pool) <-chan struct{
 func fetchMissingContent(ctx context.Context, dbConn *pgxpool.Pool) {
 	log := logging.ExtractLogger(ctx)
 
-	type query struct {
-		Message models.DiscordMessage `db:"msg"`
-	}
-	imessagesWithoutContent, err := db.Query(ctx, dbConn, query{},
+	messagesWithoutContent, err := db.Query[models.DiscordMessage](ctx, dbConn,
 		`
-		SELECT $columns
+		SELECT $columns{msg}
 		FROM
 			handmade_discordmessage AS msg
 			JOIN handmade_discorduser AS duser ON msg.user_id = duser.userid -- only fetch messages for linked discord users
@@ -95,10 +92,10 @@ func fetchMissingContent(ctx context.Context, dbConn *pgxpool.Pool) {
 		return
 	}
 
-	if len(imessagesWithoutContent) > 0 {
-		log.Info().Msgf("There are %d Discord messages without content, fetching their content now...", len(imessagesWithoutContent))
+	if len(messagesWithoutContent) > 0 {
+		log.Info().Msgf("There are %d Discord messages without content, fetching their content now...", len(messagesWithoutContent))
 	msgloop:
-		for _, imsg := range imessagesWithoutContent {
+		for _, msg := range messagesWithoutContent {
 			select {
 			case <-ctx.Done():
 				log.Info().Msg("Scrape was canceled")
@@ -106,8 +103,6 @@ func fetchMissingContent(ctx context.Context, dbConn *pgxpool.Pool) {
 			default:
 			}
 
-			msg := imsg.(*query).Message
-
 			discordMsg, err := GetChannelMessage(ctx, msg.ChannelID, msg.ID)
 			if errors.Is(err, NotFound) {
 				// This message has apparently been deleted; delete it from our database

src/discord/message_handling.go

@@ -165,7 +165,7 @@ func InternMessage(
 	dbConn db.ConnOrTx,
 	msg *Message,
 ) error {
-	_, err := db.QueryOne(ctx, dbConn, models.DiscordMessage{},
+	_, err := db.QueryOne[models.DiscordMessage](ctx, dbConn,
 		`
 		SELECT $columns
 		FROM handmade_discordmessage
@@ -219,7 +219,7 @@ type InternedMessage struct {
 }
 
 func FetchInternedMessage(ctx context.Context, dbConn db.ConnOrTx, msgId string) (*InternedMessage, error) {
-	result, err := db.QueryOne(ctx, dbConn, InternedMessage{},
+	interned, err := db.QueryOne[InternedMessage](ctx, dbConn,
 		`
 		SELECT $columns
 		FROM
@@ -235,8 +235,6 @@ func FetchInternedMessage(ctx context.Context, dbConn db.ConnOrTx, msgId string)
 	if err != nil {
 		return nil, err
 	}
-
-	interned := result.(*InternedMessage)
 	return interned, nil
 }
 
@@ -283,7 +281,7 @@ func HandleInternedMessage(ctx context.Context, dbConn db.ConnOrTx, msg *Message
 }
 
 func DeleteInternedMessage(ctx context.Context, dbConn db.ConnOrTx, interned *InternedMessage) error {
-	isnippet, err := db.QueryOne(ctx, dbConn, models.Snippet{},
+	snippet, err := db.QueryOne[models.Snippet](ctx, dbConn,
 		`
 		SELECT $columns
 		FROM handmade_snippet
@@ -294,10 +292,6 @@ func DeleteInternedMessage(ctx context.Context, dbConn db.ConnOrTx, interned *In
 	if err != nil && !errors.Is(err, db.NotFound) {
 		return oops.New(err, "failed to fetch snippet for discord message")
 	}
-	var snippet *models.Snippet
-	if !errors.Is(err, db.NotFound) {
-		snippet = isnippet.(*models.Snippet)
-	}
 
 	// NOTE(asaf): Also deletes the following through a db cascade:
 	//			   * handmade_discordmessageattachment
@@ -367,7 +361,7 @@ func SaveMessageContents(
 				return oops.New(err, "failed to create or update message contents")
 			}
 
-			icontent, err := db.QueryOne(ctx, dbConn, models.DiscordMessageContent{},
+			content, err := db.QueryOne[models.DiscordMessageContent](ctx, dbConn,
 				`
 				SELECT $columns
 				FROM
@@ -380,7 +374,7 @@ func SaveMessageContents(
 			if err != nil {
 				return oops.New(err, "failed to fetch message contents")
 			}
-			interned.MessageContent = icontent.(*models.DiscordMessageContent)
+			interned.MessageContent = content
 		}
 
 		// Save attachments
@@ -395,7 +389,7 @@ func SaveMessageContents(
 
 		// Save / delete embeds
 		if msg.OriginalHasFields("embeds") {
-			numSavedEmbeds, err := db.QueryInt(ctx, dbConn,
+			numSavedEmbeds, err := db.QueryOneScalar[int](ctx, dbConn,
 				`
 				SELECT COUNT(*)
 				FROM handmade_discordmessageembed
@@ -472,7 +466,7 @@ func saveAttachment(
 	hmnUserID int,
 	discordMessageID string,
 ) (*models.DiscordMessageAttachment, error) {
-	iexisting, err := db.QueryOne(ctx, tx, models.DiscordMessageAttachment{},
+	existing, err := db.QueryOne[models.DiscordMessageAttachment](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_discordmessageattachment
@@ -481,7 +475,7 @@ func saveAttachment(
 		attachment.ID,
 	)
 	if err == nil {
-		return iexisting.(*models.DiscordMessageAttachment), nil
+		return existing, nil
 	} else if errors.Is(err, db.NotFound) {
 		// this is fine, just create it
 	} else {
@@ -534,7 +528,7 @@ func saveAttachment(
 		return nil, oops.New(err, "failed to save Discord attachment data")
 	}
 
-	iDiscordAttachment, err := db.QueryOne(ctx, tx, models.DiscordMessageAttachment{},
+	discordAttachment, err := db.QueryOne[models.DiscordMessageAttachment](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_discordmessageattachment
@@ -546,7 +540,7 @@ func saveAttachment(
 		return nil, oops.New(err, "failed to fetch new Discord attachment data")
 	}
 
-	return iDiscordAttachment.(*models.DiscordMessageAttachment), nil
+	return discordAttachment, nil
 }
 
 // Saves an embed from Discord. NOTE: This is _not_ idempotent, so only call it
@@ -636,7 +630,7 @@ func saveEmbed(
 		return nil, oops.New(err, "failed to insert new embed")
 	}
 
-	iDiscordEmbed, err := db.QueryOne(ctx, tx, models.DiscordMessageEmbed{},
+	discordEmbed, err := db.QueryOne[models.DiscordMessageEmbed](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_discordmessageembed
@@ -648,11 +642,11 @@ func saveEmbed(
 		return nil, oops.New(err, "failed to fetch new Discord embed data")
 	}
 
-	return iDiscordEmbed.(*models.DiscordMessageEmbed), nil
+	return discordEmbed, nil
 }
 
 func FetchSnippetForMessage(ctx context.Context, dbConn db.ConnOrTx, msgID string) (*models.Snippet, error) {
-	iresult, err := db.QueryOne(ctx, dbConn, models.Snippet{},
+	snippet, err := db.QueryOne[models.Snippet](ctx, dbConn,
 		`
 		SELECT $columns
 		FROM handmade_snippet
@@ -669,7 +663,7 @@ func FetchSnippetForMessage(ctx context.Context, dbConn db.ConnOrTx, msgID strin
 		}
 	}
 
-	return iresult.(*models.Snippet), nil
+	return snippet, nil
 }
 
 /*
@@ -805,12 +799,9 @@ func HandleSnippetForInternedMessage(ctx context.Context, dbConn db.ConnOrTx, in
 			projectIDs[i] = p.Project.ID
 		}
 
-		type tagsRow struct {
-			Tag models.Tag `db:"tags"`
-		}
-		iUserTags, err := db.Query(ctx, tx, tagsRow{},
+		userTags, err := db.Query[models.Tag](ctx, tx,
 			`
-			SELECT $columns
+			SELECT $columns{tags}
 			FROM
 				tags
 				JOIN handmade_project AS project ON project.tag = tags.id
@@ -823,8 +814,7 @@ func HandleSnippetForInternedMessage(ctx context.Context, dbConn db.ConnOrTx, in
 			return oops.New(err, "failed to fetch tags for user projects")
 		}
 
-		for _, itag := range iUserTags {
-			tag := itag.(*tagsRow).Tag
+		for _, tag := range userTags {
 			allTags = append(allTags, tag.ID)
 			for _, messageTag := range messageTags {
 				if strings.EqualFold(tag.Text, messageTag) {
@@ -890,7 +880,7 @@ var RESnippetableUrl = regexp.MustCompile(`^https?://(youtu\.be|(www\.)?youtube\
 
 func getSnippetAssetOrUrl(ctx context.Context, tx db.ConnOrTx, msg *models.DiscordMessage) (*uuid.UUID, *string, error) {
 	// Check attachments
-	attachments, err := db.Query(ctx, tx, models.DiscordMessageAttachment{},
+	attachments, err := db.Query[models.DiscordMessageAttachment](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_discordmessageattachment
@@ -901,13 +891,12 @@ func getSnippetAssetOrUrl(ctx context.Context, tx db.ConnOrTx, msg *models.Disco
 	if err != nil {
 		return nil, nil, oops.New(err, "failed to fetch message attachments")
 	}
-	for _, iattachment := range attachments {
-		attachment := iattachment.(*models.DiscordMessageAttachment)
+	for _, attachment := range attachments {
 		return &attachment.AssetID, nil, nil
 	}
 
 	// Check embeds
-	embeds, err := db.Query(ctx, tx, models.DiscordMessageEmbed{},
+	embeds, err := db.Query[models.DiscordMessageEmbed](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_discordmessageembed
@@ -918,8 +907,7 @@ func getSnippetAssetOrUrl(ctx context.Context, tx db.ConnOrTx, msg *models.Disco
 	if err != nil {
 		return nil, nil, oops.New(err, "failed to fetch discord embeds")
 	}
-	for _, iembed := range embeds {
-		embed := iembed.(*models.DiscordMessageEmbed)
+	for _, embed := range embeds {
 		if embed.VideoID != nil {
 			return embed.VideoID, nil, nil
 		} else if embed.ImageID != nil {

src/hmndata/project_helper.go

@@ -140,15 +140,15 @@ func FetchProjects(
 	}
 
 	// Do the query
-	iprojects, err := db.Query(ctx, dbConn, projectRow{}, qb.String(), qb.Args()...)
+	projectRows, err := db.Query[projectRow](ctx, dbConn, qb.String(), qb.Args()...)
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch projects")
 	}
 
 	// Fetch project owners to do permission checks
-	projectIds := make([]int, len(iprojects))
-	for i, iproject := range iprojects {
-		projectIds[i] = iproject.(*projectRow).Project.ID
+	projectIds := make([]int, len(projectRows))
+	for i, p := range projectRows {
+		projectIds[i] = p.Project.ID
 	}
 	projectOwners, err := FetchMultipleProjectsOwners(ctx, tx, projectIds)
 	if err != nil {
@@ -156,8 +156,7 @@ func FetchProjects(
 	}
 
 	var res []ProjectAndStuff
-	for i, iproject := range iprojects {
-		row := iproject.(*projectRow)
+	for i, p := range projectRows {
 		owners := projectOwners[i].Owners
 
 		/*
@@ -191,10 +190,10 @@ func FetchProjects(
 		}
 
 		projectGenerallyVisible := true &&
-			row.Project.Lifecycle.In(models.VisibleProjectLifecycles) &&
-			!row.Project.Hidden &&
-			(!row.Project.Personal || allOwnersApproved || row.Project.IsHMN())
-		if row.Project.IsHMN() {
+			p.Project.Lifecycle.In(models.VisibleProjectLifecycles) &&
+			!p.Project.Hidden &&
+			(!p.Project.Personal || allOwnersApproved || p.Project.IsHMN())
+		if p.Project.IsHMN() {
 			projectGenerallyVisible = true // hard override
 		}
 
@@ -205,11 +204,11 @@ func FetchProjects(
 
 		if projectVisible {
 			res = append(res, ProjectAndStuff{
-				Project:        row.Project,
-				LogoLightAsset: row.LogoLightAsset,
-				LogoDarkAsset:  row.LogoDarkAsset,
+				Project:        p.Project,
+				LogoLightAsset: p.LogoLightAsset,
+				LogoDarkAsset:  p.LogoDarkAsset,
 				Owners:         owners,
-				Tag:            row.Tag,
+				Tag:            p.Tag,
 			})
 		}
 	}
@@ -334,7 +333,7 @@ func FetchMultipleProjectsOwners(
 		UserID    int `db:"user_id"`
 		ProjectID int `db:"project_id"`
 	}
-	iuserprojects, err := db.Query(ctx, tx, userProject{},
+	userProjects, err := db.Query[userProject](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_user_projects
@@ -348,9 +347,7 @@ func FetchMultipleProjectsOwners(
 
 	// Get the unique user IDs from this set and fetch the users from the db
 	var userIds []int
-	for _, iuserproject := range iuserprojects {
-		userProject := iuserproject.(*userProject)
-
+	for _, userProject := range userProjects {
 		addUserId := true
 		for _, uid := range userIds {
 			if uid == userProject.UserID {
@@ -361,13 +358,11 @@ func FetchMultipleProjectsOwners(
 			userIds = append(userIds, userProject.UserID)
 		}
 	}
-	type userQuery struct {
-		User models.User `db:"auth_user"`
-	}
-	iusers, err := db.Query(ctx, tx, userQuery{},
+	users, err := db.Query[models.User](ctx, tx,
 		`
-		SELECT $columns
-		FROM auth_user
+		SELECT $columns{auth_user}
+		FROM
+			auth_user
 			LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
 		WHERE
 			auth_user.id = ANY($1)
@@ -383,9 +378,7 @@ func FetchMultipleProjectsOwners(
 	for i, pid := range projectIds {
 		res[i] = ProjectOwners{ProjectID: pid}
 	}
-	for _, iuserproject := range iuserprojects {
-		userProject := iuserproject.(*userProject)
-
+	for _, userProject := range userProjects {
 		// Get a pointer to the existing record in the result
 		var projectOwners *ProjectOwners
 		for i := range res {
@@ -396,10 +389,9 @@ func FetchMultipleProjectsOwners(
 
 		// Get the full user record we fetched
 		var user *models.User
-		for _, iuser := range iusers {
-			u := iuser.(*userQuery).User
+		for _, u := range users {
 			if u.ID == userProject.UserID {
-				user = &u
+				user = u
 			}
 		}
 		if user == nil {
@@ -473,7 +465,7 @@ func SetProjectTag(
 		resultTag = p.Tag
 	} else if p.Project.TagID == nil {
 		// Create a tag
-		itag, err := db.QueryOne(ctx, tx, models.Tag{},
+		tag, err := db.QueryOne[models.Tag](ctx, tx,
 			`
 			INSERT INTO tags (text) VALUES ($1)
 			RETURNING $columns
@@ -483,7 +475,7 @@ func SetProjectTag(
 		if err != nil {
 			return nil, oops.New(err, "failed to create new tag for project")
 		}
-		resultTag = itag.(*models.Tag)
+		resultTag = tag
 
 		// Attach it to the project
 		_, err = tx.Exec(ctx,
@@ -499,7 +491,7 @@ func SetProjectTag(
 		}
 	} else {
 		// Update the text of an existing one
-		itag, err := db.QueryOne(ctx, tx, models.Tag{},
+		tag, err := db.QueryOne[models.Tag](ctx, tx,
 			`
 			UPDATE tags
 			SET text = $1
@@ -511,7 +503,7 @@ func SetProjectTag(
 		if err != nil {
 			return nil, oops.New(err, "failed to update existing tag")
 		}
-		resultTag = itag.(*models.Tag)
+		resultTag = tag
 	}
 
 	err = tx.Commit(ctx)

src/hmndata/snippet_helper.go

@@ -44,10 +44,7 @@ func FetchSnippets(
 
 	if len(q.Tags) > 0 {
 		// Get snippet IDs with this tag, then use that in the main query
-		type snippetIDRow struct {
-			SnippetID int `db:"snippet_id"`
-		}
-		iSnippetIDs, err := db.Query(ctx, tx, snippetIDRow{},
+		snippetIDs, err := db.QueryScalar[int](ctx, tx,
 			`
 			SELECT DISTINCT snippet_id
 			FROM
@@ -63,14 +60,11 @@ func FetchSnippets(
 		}
 
 		// special early-out: no snippets found for these tags at all
-		if len(iSnippetIDs) == 0 {
+		if len(snippetIDs) == 0 {
 			return nil, nil
 		}
 
-		q.IDs = make([]int, len(iSnippetIDs))
-		for i := range iSnippetIDs {
-			q.IDs[i] = iSnippetIDs[i].(*snippetIDRow).SnippetID
-		}
+		q.IDs = snippetIDs
 	}
 
 	var qb db.QueryBuilder
@@ -125,16 +119,14 @@ func FetchSnippets(
 		DiscordMessage *models.DiscordMessage `db:"discord_message"`
 	}
 
-	iresults, err := db.Query(ctx, tx, resultRow{}, qb.String(), qb.Args()...)
+	results, err := db.Query[resultRow](ctx, tx, qb.String(), qb.Args()...)
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch threads")
 	}
 
-	result := make([]SnippetAndStuff, len(iresults)) // allocate extra space because why not
-	snippetIDs := make([]int, len(iresults))
-	for i, iresult := range iresults {
-		row := *iresult.(*resultRow)
-
+	result := make([]SnippetAndStuff, len(results)) // allocate extra space because why not
+	snippetIDs := make([]int, len(results))
+	for i, row := range results {
 		result[i] = SnippetAndStuff{
 			Snippet:        row.Snippet,
 			Owner:          row.Owner,
@@ -150,7 +142,7 @@ func FetchSnippets(
 		SnippetID int         `db:"snippet_tags.snippet_id"`
 		Tag       *models.Tag `db:"tags"`
 	}
-	iSnippetTags, err := db.Query(ctx, tx, snippetTagRow{},
+	snippetTags, err := db.Query[snippetTagRow](ctx, tx,
 		`
 		SELECT $columns
 		FROM
@@ -170,8 +162,7 @@ func FetchSnippets(
 	for i := range result {
 		resultBySnippetId[result[i].Snippet.ID] = &result[i]
 	}
-	for _, iSnippetTag := range iSnippetTags {
-		snippetTag := iSnippetTag.(*snippetTagRow)
+	for _, snippetTag := range snippetTags {
 		item := resultBySnippetId[snippetTag.SnippetID]
 		item.Tags = append(item.Tags, snippetTag.Tag)
 	}

src/hmndata/tag_helper.go

@@ -40,18 +40,11 @@ func FetchTags(ctx context.Context, dbConn db.ConnOrTx, q TagQuery) ([]*models.T
 		qb.Add(`LIMIT $? OFFSET $?`, q.Limit, q.Offset)
 	}
 
-	itags, err := db.Query(ctx, dbConn, models.Tag{}, qb.String(), qb.Args()...)
+	tags, err := db.Query[models.Tag](ctx, dbConn, qb.String(), qb.Args()...)
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch tags")
 	}
-
-	res := make([]*models.Tag, len(itags))
-	for i, itag := range itags {
-		tag := itag.(*models.Tag)
-		res[i] = tag
-	}
-
-	return res, nil
+	return tags, nil
 }
 
 func FetchTag(ctx context.Context, dbConn db.ConnOrTx, q TagQuery) (*models.Tag, error) {

src/hmndata/threads_and_posts_helper.go

@@ -145,15 +145,13 @@ func FetchThreads(
 		ForumLastReadTime  *time.Time `db:"slri.lastread"`
 	}
 
-	iresults, err := db.Query(ctx, dbConn, resultRow{}, qb.String(), qb.Args()...)
+	rows, err := db.Query[resultRow](ctx, dbConn, qb.String(), qb.Args()...)
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch threads")
 	}
 
-	result := make([]ThreadAndStuff, len(iresults))
-	for i, iresult := range iresults {
-		row := *iresult.(*resultRow)
-
+	result := make([]ThreadAndStuff, len(rows))
+	for i, row := range rows {
 		hasRead := false
 		if currentUser != nil && currentUser.MarkedAllReadAt.After(row.LastPost.PostDate) {
 			hasRead = true
@@ -263,7 +261,7 @@ func CountThreads(
 		)
 	}
 
-	count, err := db.QueryInt(ctx, dbConn, qb.String(), qb.Args()...)
+	count, err := db.QueryOneScalar[int](ctx, dbConn, qb.String(), qb.Args()...)
 	if err != nil {
 		return 0, oops.New(err, "failed to fetch count of threads")
 	}
@@ -405,15 +403,13 @@ func FetchPosts(
 		qb.Add(`LIMIT $? OFFSET $?`, q.Limit, q.Offset)
 	}
 
-	iresults, err := db.Query(ctx, dbConn, resultRow{}, qb.String(), qb.Args()...)
+	rows, err := db.Query[resultRow](ctx, dbConn, qb.String(), qb.Args()...)
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch posts")
 	}
 
-	result := make([]PostAndStuff, len(iresults))
-	for i, iresult := range iresults {
-		row := *iresult.(*resultRow)
-
+	result := make([]PostAndStuff, len(rows))
+	for i, row := range rows {
 		hasRead := false
 		if currentUser != nil && currentUser.MarkedAllReadAt.After(row.Post.PostDate) {
 			hasRead = true
@@ -595,7 +591,7 @@ func CountPosts(
 		)
 	}
 
-	count, err := db.QueryInt(ctx, dbConn, qb.String(), qb.Args()...)
+	count, err := db.QueryOneScalar[int](ctx, dbConn, qb.String(), qb.Args()...)
 	if err != nil {
 		return 0, oops.New(err, "failed to count posts")
 	}
@@ -608,12 +604,9 @@ func UserCanEditPost(ctx context.Context, connOrTx db.ConnOrTx, user models.User
 		return true
 	}
 
-	type postResult struct {
-		AuthorID *int `db:"post.author_id"`
-	}
-	iresult, err := db.QueryOne(ctx, connOrTx, postResult{},
+	authorID, err := db.QueryOneScalar[*int](ctx, connOrTx,
 		`
-		SELECT $columns
+		SELECT post.author_id
 		FROM
 			handmade_post AS post
 		WHERE
@@ -629,9 +622,8 @@ func UserCanEditPost(ctx context.Context, connOrTx db.ConnOrTx, user models.User
 			panic(oops.New(err, "failed to get author of post when checking permissions"))
 		}
 	}
-	result := iresult.(*postResult)
 
-	return result.AuthorID != nil && *result.AuthorID == user.ID
+	return authorID != nil && *authorID == user.ID
 }
 
 func CreateNewPost(
@@ -709,7 +701,7 @@ func DeletePost(
 		FirstPostID int  `db:"first_id"`
 		Deleted     bool `db:"deleted"`
 	}
-	ti, err := db.QueryOne(ctx, tx, threadInfo{},
+	info, err := db.QueryOne[threadInfo](ctx, tx,
 		`
 		SELECT $columns
 		FROM
@@ -722,7 +714,6 @@ func DeletePost(
 	if err != nil {
 		panic(oops.New(err, "failed to fetch thread info"))
 	}
-	info := ti.(*threadInfo)
 	if info.Deleted {
 		return true
 	}
@@ -848,12 +839,9 @@ func CreatePostVersion(ctx context.Context, tx pgx.Tx, postId int, unparsedConte
 		keys = append(keys, key)
 	}
 
-	type assetId struct {
-		AssetID uuid.UUID `db:"id"`
-	}
-	assetResult, err := db.Query(ctx, tx, assetId{},
+	assetIDs, err := db.QueryScalar[uuid.UUID](ctx, tx,
 		`
-		SELECT $columns
+		SELECT id
 		FROM handmade_asset
 		WHERE s3_key = ANY($1)
 		`,
@@ -865,8 +853,8 @@ func CreatePostVersion(ctx context.Context, tx pgx.Tx, postId int, unparsedConte
 
 	var values [][]interface{}
 
-	for _, asset := range assetResult {
-		values = append(values, []interface{}{postId, asset.(*assetId).AssetID})
+	for _, assetID := range assetIDs {
+		values = append(values, []interface{}{postId, assetID})
 	}
 
 	_, err = tx.CopyFrom(ctx, pgx.Identifier{"handmade_post_asset_usage"}, []string{"post_id", "asset_id"}, pgx.CopyFromRows(values))
@@ -886,7 +874,7 @@ Returns errThreadEmpty if the thread contains no visible posts any more.
 You should probably mark the thread as deleted in this case.
 */
 func FixThreadPostIds(ctx context.Context, tx pgx.Tx, threadId int) error {
-	postsIter, err := db.Query(ctx, tx, models.Post{},
+	posts, err := db.Query[models.Post](ctx, tx,
 		`
 		SELECT $columns
 		FROM handmade_post
@@ -901,9 +889,7 @@ func FixThreadPostIds(ctx context.Context, tx pgx.Tx, threadId int) error {
 	}
 
 	var firstPost, lastPost *models.Post
-	for _, ipost := range postsIter {
-		post := ipost.(*models.Post)
-
+	for _, post := range posts {
 		if firstPost == nil || post.PostDate.Before(firstPost.PostDate) {
 			firstPost = post
 		}

src/hmndata/twitch.go

@@ -22,12 +22,9 @@ type TwitchStreamer struct {
 var twitchRegex = regexp.MustCompile(`twitch\.tv/(?P<login>[^/]+)$`)
 
 func FetchTwitchStreamers(ctx context.Context, dbConn db.ConnOrTx) ([]TwitchStreamer, error) {
-	type linkResult struct {
-		Link models.Link `db:"link"`
-	}
-	streamers, err := db.Query(ctx, dbConn, linkResult{},
+	dbStreamers, err := db.Query[models.Link](ctx, dbConn,
 		`
-		SELECT $columns
+		SELECT $columns{link}
 		FROM
 			handmade_links AS link
 			LEFT JOIN auth_user AS link_owner ON link_owner.id = link.user_id
@@ -49,10 +46,8 @@ func FetchTwitchStreamers(ctx context.Context, dbConn db.ConnOrTx) ([]TwitchStre
 		return nil, oops.New(err, "failed to fetch twitch links")
 	}
 
-	result := make([]TwitchStreamer, 0, len(streamers))
-	for _, s := range streamers {
-		dbStreamer := s.(*linkResult).Link
-
+	result := make([]TwitchStreamer, 0, len(dbStreamers))
+	for _, dbStreamer := range dbStreamers {
 		streamer := TwitchStreamer{
 			UserID:    dbStreamer.UserID,
 			ProjectID: dbStreamer.ProjectID,
@@ -81,7 +76,7 @@ func FetchTwitchStreamers(ctx context.Context, dbConn db.ConnOrTx) ([]TwitchStre
 }
 
 func FetchTwitchLoginsForUserOrProject(ctx context.Context, dbConn db.ConnOrTx, userId *int, projectId *int) ([]string, error) {
-	links, err := db.Query(ctx, dbConn, models.Link{},
+	links, err := db.Query[models.Link](ctx, dbConn,
 		`
 		SELECT $columns
 		FROM
@@ -100,8 +95,7 @@ func FetchTwitchLoginsForUserOrProject(ctx context.Context, dbConn db.ConnOrTx,
 	result := make([]string, 0, len(links))
 
 	for _, l := range links {
-		url := l.(*models.Link).URL
-		match := twitchRegex.FindStringSubmatch(url)
+		match := twitchRegex.FindStringSubmatch(l.URL)
 		if match != nil {
 			login := strings.ToLower(match[twitchRegex.SubexpIndex("login")])
 			result = append(result, login)

src/migration/migrations/2021-11-06T033930Z_PersonalProjects.go

@@ -110,7 +110,7 @@ func (m PersonalProjects) Up(ctx context.Context, tx pgx.Tx) error {
 	// Port "jam snippets" to use a tag
 	//
 
-	jamTagId, err := db.QueryInt(ctx, tx, `INSERT INTO tags (text) VALUES ('wheeljam') RETURNING id`)
+	jamTagId, err := db.QueryOneScalar[int](ctx, tx, `INSERT INTO tags (text) VALUES ('wheeljam') RETURNING id`)
 	if err != nil {
 		return oops.New(err, "failed to create jam tag")
 	}

src/models/subforum.go

@@ -44,14 +44,10 @@ func (node *SubforumTreeNode) GetLineage() []*Subforum {
 }
 
 func GetFullSubforumTree(ctx context.Context, conn *pgxpool.Pool) SubforumTree {
-	type subforumRow struct {
-		Subforum Subforum `db:"sf"`
-	}
-	rowsSlice, err := db.Query(ctx, conn, subforumRow{},
+	subforums, err := db.Query[Subforum](ctx, conn,
 		`
 		SELECT $columns
-		FROM
-			handmade_subforum as sf
+		FROM handmade_subforum
 		ORDER BY sort, id ASC
 		`,
 	)
@@ -59,10 +55,9 @@ func GetFullSubforumTree(ctx context.Context, conn *pgxpool.Pool) SubforumTree {
 		panic(oops.New(err, "failed to fetch subforum tree"))
 	}
 
-	sfTreeMap := make(map[int]*SubforumTreeNode, len(rowsSlice))
-	for _, row := range rowsSlice {
-		sf := row.(*subforumRow).Subforum
-		sfTreeMap[sf.ID] = &SubforumTreeNode{Subforum: sf}
+	sfTreeMap := make(map[int]*SubforumTreeNode, len(subforums))
+	for _, sf := range subforums {
+		sfTreeMap[sf.ID] = &SubforumTreeNode{Subforum: *sf}
 	}
 
 	for _, node := range sfTreeMap {
@@ -71,9 +66,8 @@ func GetFullSubforumTree(ctx context.Context, conn *pgxpool.Pool) SubforumTree {
 		}
 	}
 
-	for _, row := range rowsSlice {
+	for _, cat := range subforums {
 		// NOTE(asaf): Doing this in a separate loop over rowsSlice to ensure that Children are in db order.
-		cat := row.(*subforumRow).Subforum
 		node := sfTreeMap[cat.ID]
 		if node.Parent != nil {
 			node.Parent.Children = append(node.Parent.Children, node)

src/twitch/twitch.go

@@ -440,7 +440,7 @@ func updateStreamStatusInDB(ctx context.Context, conn db.ConnOrTx, status *strea
 	inserted := false
 	if isStatusRelevant(status) {
 		log.Debug().Msg("Status relevant")
-		_, err := db.QueryOne(ctx, conn, models.TwitchStream{},
+		_, err := db.QueryOne[models.TwitchStream](ctx, conn,
 			`
 			SELECT $columns
 			FROM twitch_streams

src/website/admin.go

@@ -207,7 +207,7 @@ func AdminApprovalQueue(c *RequestContext) ResponseData {
 		userIds = append(userIds, u.User.ID)
 	}
 
-	userLinks, err := db.Query(c.Context(), c.Conn, models.Link{},
+	userLinks, err := db.Query[models.Link](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -222,8 +222,7 @@ func AdminApprovalQueue(c *RequestContext) ResponseData {
 		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch user links"))
 	}
 
-	for _, ul := range userLinks {
-		link := ul.(*models.Link)
+	for _, link := range userLinks {
 		userData := unapprovedUsers[userIDToDataIdx[*link.UserID]]
 		userData.UserLinks = append(userData.UserLinks, templates.LinkToTemplate(link))
 	}
@@ -257,12 +256,9 @@ func AdminApprovalQueueSubmit(c *RequestContext) ResponseData {
 		return RejectRequest(c, "User id can't be parsed")
 	}
 
-	type userQuery struct {
-		User models.User `db:"auth_user"`
-	}
-	u, err := db.QueryOne(c.Context(), c.Conn, userQuery{},
+	user, err := db.QueryOne[models.User](c.Context(), c.Conn,
 		`
-		SELECT $columns
+		SELECT $columns{auth_user}
 			FROM auth_user
 			LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
 		WHERE auth_user.id = $1
@@ -276,7 +272,6 @@ func AdminApprovalQueueSubmit(c *RequestContext) ResponseData {
 			return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch user"))
 		}
 	}
-	user := u.(*userQuery).User
 
 	whatHappened := ""
 	if action == ApprovalQueueActionApprove {
@@ -337,7 +332,7 @@ type UnapprovedPost struct {
 }
 
 func fetchUnapprovedPosts(c *RequestContext) ([]*UnapprovedPost, error) {
-	it, err := db.Query(c.Context(), c.Conn, UnapprovedPost{},
+	posts, err := db.Query[UnapprovedPost](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -358,11 +353,7 @@ func fetchUnapprovedPosts(c *RequestContext) ([]*UnapprovedPost, error) {
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch unapproved posts")
 	}
-	var res []*UnapprovedPost
-	for _, iresult := range it {
-		res = append(res, iresult.(*UnapprovedPost))
-	}
-	return res, nil
+	return posts, nil
 }
 
 type UnapprovedProject struct {
@@ -372,12 +363,9 @@ type UnapprovedProject struct {
 }
 
 func fetchUnapprovedProjects(c *RequestContext) ([]UnapprovedProject, error) {
-	type unapprovedUser struct {
-		ID int `db:"id"`
-	}
-	it, err := db.Query(c.Context(), c.Conn, unapprovedUser{},
+	ownerIDs, err := db.QueryScalar[int](c.Context(), c.Conn,
 		`
-		SELECT $columns
+		SELECT id
 		FROM
 			auth_user AS u
 		WHERE
@@ -388,10 +376,6 @@ func fetchUnapprovedProjects(c *RequestContext) ([]UnapprovedProject, error) {
 	if err != nil {
 		return nil, oops.New(err, "failed to fetch unapproved users")
 	}
-	ownerIDs := make([]int, 0, len(it))
-	for _, uid := range it {
-		ownerIDs = append(ownerIDs, uid.(*unapprovedUser).ID)
-	}
 
 	projects, err := hmndata.FetchProjects(c.Context(), c.Conn, c.CurrentUser, hmndata.ProjectsQuery{
 		OwnerIDs:      ownerIDs,
@@ -406,7 +390,7 @@ func fetchUnapprovedProjects(c *RequestContext) ([]UnapprovedProject, error) {
 		projectIDs = append(projectIDs, p.Project.ID)
 	}
 
-	projectLinks, err := db.Query(c.Context(), c.Conn, models.Link{},
+	projectLinks, err := db.Query[models.Link](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -425,8 +409,7 @@ func fetchUnapprovedProjects(c *RequestContext) ([]UnapprovedProject, error) {
 
 	for idx, proj := range projects {
 		links := make([]*models.Link, 0, 10) // NOTE(asaf): 10 should be enough for most projects.
-		for _, l := range projectLinks {
-			link := l.(*models.Link)
+		for _, link := range projectLinks {
 			if *link.ProjectID == proj.Project.ID {
 				links = append(links, link)
 			}
@@ -455,7 +438,7 @@ func deleteAllPostsForUser(ctx context.Context, conn *pgxpool.Pool, userId int)
 		ThreadID int `db:"thread.id"`
 		PostID   int `db:"post.id"`
 	}
-	it, err := db.Query(ctx, tx, toDelete{},
+	rows, err := db.Query[toDelete](ctx, tx,
 		`
 		SELECT $columns
 		FROM
@@ -471,8 +454,7 @@ func deleteAllPostsForUser(ctx context.Context, conn *pgxpool.Pool, userId int)
 		return oops.New(err, "failed to fetch posts to delete for user")
 	}
 
-	for _, iResult := range it {
-		row := iResult.(*toDelete)
+	for _, row := range rows {
 		hmndata.DeletePost(ctx, tx, row.ThreadID, row.PostID)
 	}
 	err = tx.Commit(ctx)
@@ -489,9 +471,9 @@ func deleteAllProjectsForUser(ctx context.Context, conn *pgxpool.Pool, userId in
 	}
 	defer tx.Rollback(ctx)
 
-	toDelete, err := db.Query(ctx, tx, models.Project{},
+	projectIDsToDelete, err := db.QueryScalar[int](ctx, tx,
 		`
-		SELECT $columns
+		SELECT project.id
 		FROM
 			handmade_project AS project
 			JOIN handmade_user_projects AS up ON up.project_id = project.id
@@ -504,17 +486,12 @@ func deleteAllProjectsForUser(ctx context.Context, conn *pgxpool.Pool, userId in
 		return oops.New(err, "failed to fetch user's projects")
 	}
 
-	var projectIds []int
-	for _, p := range toDelete {
-		projectIds = append(projectIds, p.(*models.Project).ID)
-	}
-
-	if len(projectIds) > 0 {
+	if len(projectIDsToDelete) > 0 {
 		_, err = tx.Exec(ctx,
 			`
 			DELETE FROM handmade_project WHERE id = ANY($1)
 			`,
-			projectIds,
+			projectIDsToDelete,
 		)
 		if err != nil {
 			return oops.New(err, "failed to delete user's projects")

src/website/api.go

@@ -19,12 +19,9 @@ func APICheckUsername(c *RequestContext) ResponseData {
 		requestedUsername := usernameArgs[0]
 		found = true
 		c.Perf.StartBlock("SQL", "Fetch user")
-		type userQuery struct {
-			User models.User `db:"auth_user"`
-		}
-		userResult, err := db.QueryOne(c.Context(), c.Conn, userQuery{},
+		user, err := db.QueryOne[models.User](c.Context(), c.Conn,
 			`
-			SELECT $columns
+			SELECT $columns{auth_user}
 			FROM
 				auth_user
 				LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
@@ -43,7 +40,7 @@ func APICheckUsername(c *RequestContext) ResponseData {
 				return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch user: %s", requestedUsername))
 			}
 		} else {
-			canonicalUsername = userResult.(*userQuery).User.Username
+			canonicalUsername = user.Username
 		}
 	}
 

src/website/auth.go

@@ -75,13 +75,11 @@ func Login(c *RequestContext) ResponseData {
 		return res
 	}
 
-	type userQuery struct {
-		User models.User `db:"auth_user"`
-	}
-	userRow, err := db.QueryOne(c.Context(), c.Conn, userQuery{},
+	user, err := db.QueryOne[models.User](c.Context(), c.Conn,
 		`
-		SELECT $columns
-			FROM auth_user
+		SELECT $columns{auth_user}
+		FROM
+			auth_user
 			LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
 		WHERE LOWER(username) = LOWER($1)
 		`,
@@ -94,7 +92,6 @@ func Login(c *RequestContext) ResponseData {
 			return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to look up user by username"))
 		}
 	}
-	user := &userRow.(*userQuery).User
 
 	success, err := tryLogin(c, user, password)
 
@@ -174,7 +171,7 @@ func RegisterNewUserSubmit(c *RequestContext) ResponseData {
 
 	c.Perf.StartBlock("SQL", "Check for existing usernames and emails")
 	userAlreadyExists := true
-	_, err := db.QueryInt(c.Context(), c.Conn,
+	_, err := db.QueryOneScalar[int](c.Context(), c.Conn,
 		`
 		SELECT id
 		FROM auth_user
@@ -195,7 +192,7 @@ func RegisterNewUserSubmit(c *RequestContext) ResponseData {
 	}
 
 	emailAlreadyExists := true
-	_, err = db.QueryInt(c.Context(), c.Conn,
+	_, err = db.QueryOneScalar[int](c.Context(), c.Conn,
 		`
 		SELECT id
 		FROM auth_user
@@ -454,16 +451,15 @@ func RequestPasswordResetSubmit(c *RequestContext) ResponseData {
 		return RejectRequest(c, "You must provide a username and an email address.")
 	}
 
-	var user *models.User
-
 	c.Perf.StartBlock("SQL", "Fetching user")
 	type userQuery struct {
 		User models.User `db:"auth_user"`
 	}
-	userRow, err := db.QueryOne(c.Context(), c.Conn, userQuery{},
+	user, err := db.QueryOne[models.User](c.Context(), c.Conn,
 		`
-		SELECT $columns
-		FROM auth_user
+		SELECT $columns{auth_user}
+		FROM
+			auth_user
 			LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
 		WHERE
 			LOWER(username) = LOWER($1)
@@ -478,13 +474,10 @@ func RequestPasswordResetSubmit(c *RequestContext) ResponseData {
 			return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to look up user by username"))
 		}
 	}
-	if userRow != nil {
-		user = &userRow.(*userQuery).User
-	}
 
 	if user != nil {
 		c.Perf.StartBlock("SQL", "Fetching existing token")
-		tokenRow, err := db.QueryOne(c.Context(), c.Conn, models.OneTimeToken{},
+		resetToken, err := db.QueryOne[models.OneTimeToken](c.Context(), c.Conn,
 			`
 			SELECT $columns
 			FROM handmade_onetimetoken
@@ -501,10 +494,6 @@ func RequestPasswordResetSubmit(c *RequestContext) ResponseData {
 				return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch onetimetoken for user"))
 			}
 		}
-		var resetToken *models.OneTimeToken
-		if tokenRow != nil {
-			resetToken = tokenRow.(*models.OneTimeToken)
-		}
 		now := time.Now()
 
 		if resetToken != nil {
@@ -527,7 +516,7 @@ func RequestPasswordResetSubmit(c *RequestContext) ResponseData {
 
 		if resetToken == nil {
 			c.Perf.StartBlock("SQL", "Creating new token")
-			tokenRow, err := db.QueryOne(c.Context(), c.Conn, models.OneTimeToken{},
+			newToken, err := db.QueryOne[models.OneTimeToken](c.Context(), c.Conn,
 				`
 				INSERT INTO handmade_onetimetoken (token_type, created, expires, token_content, owner_id)
 				VALUES ($1, $2, $3, $4, $5)
@@ -543,7 +532,7 @@ func RequestPasswordResetSubmit(c *RequestContext) ResponseData {
 			if err != nil {
 				return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to create onetimetoken"))
 			}
-			resetToken = tokenRow.(*models.OneTimeToken)
+			resetToken = newToken
 
 			err = email.SendPasswordReset(user.Email, user.BestName(), user.Username, resetToken.Content, resetToken.Expires, c.Perf)
 			if err != nil {
@@ -787,7 +776,7 @@ func validateUsernameAndToken(c *RequestContext, username string, token string,
 		User         models.User          `db:"auth_user"`
 		OneTimeToken *models.OneTimeToken `db:"onetimetoken"`
 	}
-	row, err := db.QueryOne(c.Context(), c.Conn, userAndTokenQuery{},
+	data, err := db.QueryOne[userAndTokenQuery](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM auth_user
@@ -807,8 +796,7 @@ func validateUsernameAndToken(c *RequestContext, username string, token string,
 			return result
 		}
 	}
-	if row != nil {
-		data := row.(*userAndTokenQuery)
+	if data != nil {
 		result.User = &data.User
 		result.OneTimeToken = data.OneTimeToken
 		if result.OneTimeToken != nil {

src/website/blogs.go

@@ -558,7 +558,7 @@ func getCommonBlogData(c *RequestContext) (commonBlogData, bool) {
 		res.ThreadID = threadId
 
 		c.Perf.StartBlock("SQL", "Verify that the thread exists")
-		threadExists, err := db.QueryBool(c.Context(), c.Conn,
+		threadExists, err := db.QueryOneScalar[bool](c.Context(), c.Conn,
 			`
 			SELECT COUNT(*) > 0
 			FROM handmade_thread
@@ -586,7 +586,7 @@ func getCommonBlogData(c *RequestContext) (commonBlogData, bool) {
 		res.PostID = postId
 
 		c.Perf.StartBlock("SQL", "Verify that the post exists")
-		postExists, err := db.QueryBool(c.Context(), c.Conn,
+		postExists, err := db.QueryOneScalar[bool](c.Context(), c.Conn,
 			`
 			SELECT COUNT(*) > 0
 			FROM handmade_post

src/website/discord.go

@@ -104,7 +104,7 @@ func DiscordUnlink(c *RequestContext) ResponseData {
 	}
 	defer tx.Rollback(c.Context())
 
-	iDiscordUser, err := db.QueryOne(c.Context(), tx, models.DiscordUser{},
+	discordUser, err := db.QueryOne[models.DiscordUser](c.Context(), tx,
 		`
 		SELECT $columns
 		FROM handmade_discorduser
@@ -119,7 +119,6 @@ func DiscordUnlink(c *RequestContext) ResponseData {
 			return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to get Discord user for unlink"))
 		}
 	}
-	discordUser := iDiscordUser.(*models.DiscordUser)
 
 	_, err = tx.Exec(c.Context(),
 		`
@@ -146,7 +145,7 @@ func DiscordUnlink(c *RequestContext) ResponseData {
 }
 
 func DiscordShowcaseBacklog(c *RequestContext) ResponseData {
-	iduser, err := db.QueryOne(c.Context(), c.Conn, models.DiscordUser{},
+	duser, err := db.QueryOne[models.DiscordUser](c.Context(), c.Conn,
 		`SELECT $columns FROM handmade_discorduser WHERE hmn_user_id = $1`,
 		c.CurrentUser.ID,
 	)
@@ -157,14 +156,10 @@ func DiscordShowcaseBacklog(c *RequestContext) ResponseData {
 	} else if err != nil {
 		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to get discord user"))
 	}
-	duser := iduser.(*models.DiscordUser)
 
-	type messageIdQuery struct {
-		MessageID string `db:"msg.id"`
-	}
-	iMsgIDs, err := db.Query(c.Context(), c.Conn, messageIdQuery{},
+	msgIDs, err := db.QueryScalar[string](c.Context(), c.Conn,
 		`
-		SELECT $columns
+		SELECT msg.id
 		FROM
 			handmade_discordmessage AS msg
 		WHERE
@@ -178,10 +173,6 @@ func DiscordShowcaseBacklog(c *RequestContext) ResponseData {
 		return c.ErrorResponse(http.StatusInternalServerError, err)
 	}
 
-	var msgIDs []string
-	for _, imsgId := range iMsgIDs {
-		msgIDs = append(msgIDs, imsgId.(*messageIdQuery).MessageID)
-	}
 	for _, msgID := range msgIDs {
 		interned, err := discord.FetchInternedMessage(c.Context(), c.Conn, msgID)
 		if err != nil && !errors.Is(err, db.NotFound) {

src/website/forums.go

@@ -936,7 +936,7 @@ func addForumUrlsToPost(urlContext *hmnurl.UrlContext, p *templates.Post, subfor
 // Takes a template post and adds information about how many posts the user has made
 // on the site.
 func addAuthorCountsToPost(ctx context.Context, conn db.ConnOrTx, p *templates.Post) {
-	numPosts, err := db.QueryInt(ctx, conn,
+	numPosts, err := db.QueryOneScalar[int](ctx, conn,
 		`
 		SELECT COUNT(*)
 		FROM
@@ -956,7 +956,7 @@ func addAuthorCountsToPost(ctx context.Context, conn db.ConnOrTx, p *templates.P
 		p.AuthorNumPosts = numPosts
 	}
 
-	numProjects, err := db.QueryInt(ctx, conn,
+	numProjects, err := db.QueryOneScalar[int](ctx, conn,
 		`
 		SELECT COUNT(*)
 		FROM

src/website/imagefile_helper.go

@@ -89,8 +89,7 @@ func SaveImageFile(c *RequestContext, dbConn db.ConnOrTx, fileFieldName string,
 		img.Seek(0, io.SeekStart)
 		io.Copy(hasher, img) // NOTE(asaf): Writing to hash.Hash never returns an error according to the docs
 		sha1sum := hasher.Sum(nil)
-		// TODO(db): Should use insert helper
-		imageFile, err := db.QueryOne(c.Context(), dbConn, models.ImageFile{},
+		imageFile, err := db.QueryOne[models.ImageFile](c.Context(), dbConn,
 			`
 			INSERT INTO handmade_imagefile (file, size, sha1sum, protected, width, height)
 			VALUES ($1, $2, $3, $4, $5, $6)
@@ -105,7 +104,7 @@ func SaveImageFile(c *RequestContext, dbConn db.ConnOrTx, fileFieldName string,
 		}
 
 		return SaveImageFileResult{
-			ImageFile: imageFile.(*models.ImageFile),
+			ImageFile: imageFile,
 		}
 	}
 

src/website/links_helper.go

@@ -30,10 +30,9 @@ func ParseLinks(text string) []ParsedLink {
 	return res
 }
 
-func LinksToText(links []interface{}) string {
+func LinksToText(links []*models.Link) string {
 	linksText := ""
-	for _, l := range links {
-		link := l.(*models.Link)
+	for _, link := range links {
 		linksText += fmt.Sprintf("%s %s\n", link.URL, link.Name)
 	}
 	return linksText

src/website/podcast.go

@@ -532,10 +532,11 @@ func FetchPodcast(c *RequestContext, projectId int, fetchEpisodes bool, episodeG
 		Podcast       models.Podcast `db:"podcast"`
 		ImageFilename string         `db:"imagefile.file"`
 	}
-	podcastQueryResult, err := db.QueryOne(c.Context(), c.Conn, podcastQuery{},
+	podcastQueryResult, err := db.QueryOne[podcastQuery](c.Context(), c.Conn,
 		`
 		SELECT $columns
-		FROM handmade_podcast AS podcast
+		FROM
+			handmade_podcast AS podcast
 			LEFT JOIN handmade_imagefile AS imagefile ON imagefile.id = podcast.image_id
 		WHERE podcast.project_id = $1
 		`,
@@ -549,18 +550,15 @@ func FetchPodcast(c *RequestContext, projectId int, fetchEpisodes bool, episodeG
 			return result, oops.New(err, "failed to fetch podcast")
 		}
 	}
-	podcast := podcastQueryResult.(*podcastQuery).Podcast
-	podcastImageFilename := podcastQueryResult.(*podcastQuery).ImageFilename
+	podcast := podcastQueryResult.Podcast
+	podcastImageFilename := podcastQueryResult.ImageFilename
 	result.Podcast = &podcast
 	result.ImageFile = podcastImageFilename
 
 	if fetchEpisodes {
-		type podcastEpisodeQuery struct {
-			Episode models.PodcastEpisode `db:"episode"`
-		}
 		if episodeGUID == "" {
 			c.Perf.StartBlock("SQL", "Fetch podcast episodes")
-			podcastEpisodeQueryResult, err := db.Query(c.Context(), c.Conn, podcastEpisodeQuery{},
+			episodes, err := db.Query[models.PodcastEpisode](c.Context(), c.Conn,
 				`
 				SELECT $columns
 				FROM handmade_podcastepisode AS episode
@@ -573,16 +571,14 @@ func FetchPodcast(c *RequestContext, projectId int, fetchEpisodes bool, episodeG
 			if err != nil {
 				return result, oops.New(err, "failed to fetch podcast episodes")
 			}
-			for _, episodeRow := range podcastEpisodeQueryResult {
-				result.Episodes = append(result.Episodes, &episodeRow.(*podcastEpisodeQuery).Episode)
-			}
+			result.Episodes = episodes
 		} else {
 			guid, err := uuid.Parse(episodeGUID)
 			if err != nil {
 				return result, err
 			}
 			c.Perf.StartBlock("SQL", "Fetch podcast episode")
-			podcastEpisodeQueryResult, err := db.QueryOne(c.Context(), c.Conn, podcastEpisodeQuery{},
+			episode, err := db.QueryOne[models.PodcastEpisode](c.Context(), c.Conn,
 				`
 				SELECT $columns
 				FROM handmade_podcastepisode AS episode
@@ -599,8 +595,7 @@ func FetchPodcast(c *RequestContext, projectId int, fetchEpisodes bool, episodeG
 					return result, oops.New(err, "failed to fetch podcast episode")
 				}
 			}
-			episode := podcastEpisodeQueryResult.(*podcastEpisodeQuery).Episode
-			result.Episodes = append(result.Episodes, &episode)
+			result.Episodes = append(result.Episodes, episode)
 		}
 	}
 

src/website/projects.go

@@ -187,12 +187,9 @@ func ProjectHomepage(c *RequestContext) ResponseData {
 	}
 
 	c.Perf.StartBlock("SQL", "Fetching screenshots")
-	type screenshotQuery struct {
-		Filename string `db:"screenshot.file"`
-	}
-	screenshotQueryResult, err := db.Query(c.Context(), c.Conn, screenshotQuery{},
+	screenshotFilenames, err := db.QueryScalar[string](c.Context(), c.Conn,
 		`
-		SELECT $columns
+		SELECT screenshot.file
 		FROM
 			handmade_imagefile AS screenshot
 			INNER JOIN handmade_project_screenshots ON screenshot.id = handmade_project_screenshots.imagefile_id
@@ -207,10 +204,7 @@ func ProjectHomepage(c *RequestContext) ResponseData {
 	c.Perf.EndBlock()
 
 	c.Perf.StartBlock("SQL", "Fetching project links")
-	type projectLinkQuery struct {
-		Link models.Link `db:"link"`
-	}
-	projectLinkResult, err := db.Query(c.Context(), c.Conn, projectLinkQuery{},
+	projectLinks, err := db.Query[models.Link](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -237,7 +231,7 @@ func ProjectHomepage(c *RequestContext) ResponseData {
 		Thread models.Thread `db:"thread"`
 		Author models.User   `db:"author"`
 	}
-	postQueryResult, err := db.Query(c.Context(), c.Conn, postQuery{},
+	posts, err := db.Query[postQuery](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -318,21 +312,21 @@ func ProjectHomepage(c *RequestContext) ResponseData {
 		}
 	}
 
-	for _, screenshot := range screenshotQueryResult {
-		templateData.Screenshots = append(templateData.Screenshots, hmnurl.BuildUserFile(screenshot.(*screenshotQuery).Filename))
+	for _, screenshotFilename := range screenshotFilenames {
+		templateData.Screenshots = append(templateData.Screenshots, hmnurl.BuildUserFile(screenshotFilename))
 	}
 
-	for _, link := range projectLinkResult {
-		templateData.ProjectLinks = append(templateData.ProjectLinks, templates.LinkToTemplate(&link.(*projectLinkQuery).Link))
+	for _, link := range projectLinks {
+		templateData.ProjectLinks = append(templateData.ProjectLinks, templates.LinkToTemplate(link))
 	}
 
-	for _, post := range postQueryResult {
+	for _, post := range posts {
 		templateData.RecentActivity = append(templateData.RecentActivity, PostToTimelineItem(
 			c.UrlContext,
 			lineageBuilder,
-			&post.(*postQuery).Post,
-			&post.(*postQuery).Thread,
-			&post.(*postQuery).Author,
+			&post.Post,
+			&post.Thread,
+			&post.Author,
 			c.Theme,
 		))
 	}
@@ -498,7 +492,7 @@ func ProjectEdit(c *RequestContext) ResponseData {
 	}
 
 	c.Perf.StartBlock("SQL", "Fetching project links")
-	projectLinkResult, err := db.Query(c.Context(), c.Conn, models.Link{},
+	projectLinks, err := db.Query[models.Link](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -525,7 +519,7 @@ func ProjectEdit(c *RequestContext) ResponseData {
 		c.Theme,
 	)
 
-	projectSettings.LinksText = LinksToText(projectLinkResult)
+	projectSettings.LinksText = LinksToText(projectLinks)
 
 	var res ResponseData
 	res.MustWriteTemplate("project_edit.html", ProjectEditData{
@@ -822,13 +816,11 @@ func updateProject(ctx context.Context, tx pgx.Tx, user *models.User, payload *P
 		}
 	}
 
-	type userQuery struct {
-		User models.User `db:"auth_user"`
-	}
-	ownerRows, err := db.Query(ctx, tx, userQuery{},
+	owners, err := db.Query[models.User](ctx, tx,
 		`
-		SELECT $columns
-		FROM auth_user
+		SELECT $columns{auth_user}
+		FROM
+			auth_user
 			LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
 		WHERE LOWER(username) = ANY ($1)
 		`,
@@ -849,7 +841,7 @@ func updateProject(ctx context.Context, tx pgx.Tx, user *models.User, payload *P
 		return oops.New(err, "Failed to delete project owners")
 	}
 
-	for _, ownerRow := range ownerRows {
+	for _, owner := range owners {
 		_, err = tx.Exec(ctx,
 			`
 			INSERT INTO handmade_user_projects
@@ -857,7 +849,7 @@ func updateProject(ctx context.Context, tx pgx.Tx, user *models.User, payload *P
 			VALUES
 				($1,      $2)
 			`,
-			ownerRow.(*userQuery).User.ID,
+			owner.ID,
 			payload.ProjectID,
 		)
 		if err != nil {

src/website/routes.go

@@ -548,13 +548,11 @@ func getCurrentUserAndSession(c *RequestContext, sessionId string) (*models.User
 		}
 	}
 
-	type userQuery struct {
-		User models.User `db:"auth_user"`
-	}
-	userRow, err := db.QueryOne(c.Context(), c.Conn, userQuery{},
+	user, err := db.QueryOne[models.User](c.Context(), c.Conn,
 		`
-		SELECT $columns
-			FROM auth_user
+		SELECT $columns{auth_user}
+		FROM
+			auth_user
 			LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
 		WHERE username = $1
 		`,
@@ -568,7 +566,6 @@ func getCurrentUserAndSession(c *RequestContext, sessionId string) (*models.User
 			return nil, nil, oops.New(err, "failed to get user for session")
 		}
 	}
-	user := &userRow.(*userQuery).User
 
 	return user, session, nil
 }

src/website/twitch.go

@@ -70,7 +70,7 @@ func TwitchEventSubCallback(c *RequestContext) ResponseData {
 }
 
 func TwitchDebugPage(c *RequestContext) ResponseData {
-	streams, err := db.Query(c.Context(), c.Conn, models.TwitchStream{},
+	streams, err := db.Query[models.TwitchStream](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -83,8 +83,7 @@ func TwitchDebugPage(c *RequestContext) ResponseData {
 	}
 
 	html := ""
-	for _, stream := range streams {
-		s := stream.(*models.TwitchStream)
+	for _, s := range streams {
 		html += fmt.Sprintf(`<a href="https://twitch.tv/%s">%s</a>%s<br />`, s.Login, s.Login, s.Title)
 	}
 	var res ResponseData

src/website/user.go

@@ -53,12 +53,9 @@ func UserProfile(c *RequestContext) ResponseData {
 		profileUser = c.CurrentUser
 	} else {
 		c.Perf.StartBlock("SQL", "Fetch user")
-		type userQuery struct {
-			User models.User `db:"auth_user"`
-		}
-		userResult, err := db.QueryOne(c.Context(), c.Conn, userQuery{},
+		user, err := db.QueryOne[models.User](c.Context(), c.Conn,
 			`
-			SELECT $columns
+			SELECT $columns{auth_user}
 			FROM
 				auth_user
 				LEFT JOIN handmade_asset AS auth_user_avatar ON auth_user_avatar.id = auth_user.avatar_asset_id
@@ -75,7 +72,7 @@ func UserProfile(c *RequestContext) ResponseData {
 				return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch user: %s", username))
 			}
 		}
-		profileUser = &userResult.(*userQuery).User
+		profileUser = user
 	}
 
 	{
@@ -87,10 +84,7 @@ func UserProfile(c *RequestContext) ResponseData {
 	}
 
 	c.Perf.StartBlock("SQL", "Fetch user links")
-	type userLinkQuery struct {
-		UserLink models.Link `db:"link"`
-	}
-	userLinksSlice, err := db.Query(c.Context(), c.Conn, userLinkQuery{},
+	userLinks, err := db.Query[models.Link](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM
@@ -104,9 +98,9 @@ func UserProfile(c *RequestContext) ResponseData {
 	if err != nil {
 		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch links for user: %s", username))
 	}
-	profileUserLinks := make([]templates.Link, 0, len(userLinksSlice))
-	for _, l := range userLinksSlice {
-		profileUserLinks = append(profileUserLinks, templates.LinkToTemplate(&l.(*userLinkQuery).UserLink))
+	profileUserLinks := make([]templates.Link, 0, len(userLinks))
+	for _, l := range userLinks {
+		profileUserLinks = append(profileUserLinks, templates.LinkToTemplate(l))
 	}
 	c.Perf.EndBlock()
 
@@ -231,7 +225,7 @@ func UserSettings(c *RequestContext) ResponseData {
 		DiscordShowcaseBacklogUrl string
 	}
 
-	links, err := db.Query(c.Context(), c.Conn, models.Link{},
+	links, err := db.Query[models.Link](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM handmade_links
@@ -248,7 +242,7 @@ func UserSettings(c *RequestContext) ResponseData {
 
 	var tduser *templates.DiscordUser
 	var numUnsavedMessages int
-	iduser, err := db.QueryOne(c.Context(), c.Conn, models.DiscordUser{},
+	duser, err := db.QueryOne[models.DiscordUser](c.Context(), c.Conn,
 		`
 		SELECT $columns
 		FROM handmade_discorduser
@@ -261,11 +255,10 @@ func UserSettings(c *RequestContext) ResponseData {
 	} else if err != nil {
 		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch user's Discord account"))
 	} else {
-		duser := iduser.(*models.DiscordUser)
 		tmp := templates.DiscordUserToTemplate(duser)
 		tduser = &tmp
 
-		numUnsavedMessages, err = db.QueryInt(c.Context(), c.Conn,
+		numUnsavedMessages, err = db.QueryOneScalar[int](c.Context(), c.Conn,
 			`
 			SELECT COUNT(*)
 			FROM