feat: add "use_interface_return_types" option

Add an option to direct sqlc generation to use the querier interface for the return type of the WithTx method on the Queries struct.

Include WithTx in the Querier interface (when "emit_methods_with_db_argument" is false)

Author: Jesse0Michael

docs/reference/config.md

@@ -141,6 +141,8 @@ The `gen` mapping supports the following keys:
   - If true, include support for prepared queries. Defaults to `false`.
 - `emit_interface`:
   - If true, output a `Querier` interface in the generated package. Defaults to `false`.
+- `use_interface_return_types`:
+  - If true, output will use the `Querier` interface as the return type the methods in the generated package. Defaults to `false`.
 - `emit_exact_table_names`:
   - If true, struct names will mirror table names. Otherwise, sqlc attempts to singularize plural table names. Defaults to `false`.
 - `emit_empty_slices`:

examples/batch/postgresql/querier.go

@@ -39,6 +39,7 @@ type tmplCtx struct {
 	EmitAllEnumValues         bool
 	UsesCopyFrom              bool
 	UsesBatch                 bool
+	UseInterfaceReturnTypes   bool
 	OmitSqlcVersion           bool
 	BuildTags                 string
 }
@@ -169,6 +170,7 @@ func generate(req *plugin.GenerateRequest, options *opts.Options, enums []Enum,
 
 	tctx := tmplCtx{
 		EmitInterface:             options.EmitInterface,
+		UseInterfaceReturnTypes:   options.UseInterfaceReturnTypes,
 		EmitJSONTags:              options.EmitJsonTags,
 		JsonTagsIDUppercase:       options.JsonTagsIdUppercase,
 		EmitDBTags:                options.EmitDbTags,

examples/ondeck/mysql/querier.go

@@ -268,6 +268,16 @@ func (i *importer) interfaceImports() fileImports {
 
 	std["context"] = struct{}{}
 
+	sqlpkg := parseDriver(i.Options.SqlPackage)
+	switch sqlpkg {
+	case SQLDriverPGXV4:
+		pkg[ImportSpec{Path: "github.com/jackc/pgx/v4"}] = struct{}{}
+	case SQLDriverPGXV5:
+		pkg[ImportSpec{Path: "github.com/jackc/pgx/v5"}] = struct{}{}
+	default:
+		std["database/sql"] = struct{}{}
+	}
+
 	return sortedImports(std, pkg)
 }
 

examples/ondeck/postgresql/querier.go

@@ -11,6 +11,7 @@ import (
 
 type Options struct {
 	EmitInterface               bool              `json:"emit_interface" yaml:"emit_interface"`
+	UseInterfaceReturnTypes     bool              `json:"use_interface_return_types" yaml:"use_interface_return_types"`
 	EmitJsonTags                bool              `json:"emit_json_tags" yaml:"emit_json_tags"`
 	JsonTagsIdUppercase         bool              `json:"json_tags_id_uppercase" yaml:"json_tags_id_uppercase"`
 	EmitDbTags                  bool              `json:"emit_db_tags" yaml:"emit_db_tags"`

examples/ondeck/sqlite/querier.go

@@ -28,7 +28,11 @@ type Queries struct {
 }
 
 {{if not .EmitMethodsWithDBArgument}}
+{{- if and .EmitInterface .UseInterfaceReturnTypes}}
+func (q *Queries) WithTx(tx pgx.Tx) Querier {
+{{- else -}}
 func (q *Queries) WithTx(tx pgx.Tx) *Queries {
+{{- end}}
 	return &Queries{
 		db: tx,
 	}

internal/codegen/golang/gen.go

@@ -1,5 +1,10 @@
 {{define "interfaceCodePgx"}}
     type Querier interface {
+    {{- if .UseInterfaceReturnTypes}}
+        WithTx(tx pgx.Tx) Querier
+    {{- else -}}
+        WithTx(tx pgx.Tx) *Queries
+    {{- end}}
     {{- $dbtxParam := .EmitMethodsWithDBArgument -}}
     {{- range .GoQueries}}
         {{- if and (eq .Cmd ":one") ($dbtxParam) }}