feat(codegen/go): support emit_pointers_for_null_types for nullable enums

When emit_pointers_for_null_types is enabled, nullable enum columns now
generate *EnumType pointers instead of NullEnumType wrapper structs.
Previously, this setting only affected built-in types (sql.NullString ->
*string), leaving enum types unaffected.

Closes #3276

Author: winens

internal/codegen/golang/gen.go

@@ -42,6 +42,7 @@ type tmplCtx struct {
 	OmitSqlcVersion           bool
 	BuildTags                 string
 	WrapErrors                bool
+	EmitPointersForNullTypes  bool
 }
 
 func (t *tmplCtx) OutputQuery(sourceName string) bool {
@@ -140,7 +141,9 @@ func validate(options *opts.Options, enums []Enum, structs []Struct, queries []Q
 	enumNames := make(map[string]struct{})
 	for _, enum := range enums {
 		enumNames[enum.Name] = struct{}{}
-		enumNames["Null"+enum.Name] = struct{}{}
+		if !options.EmitPointersForNullTypes {
+			enumNames["Null"+enum.Name] = struct{}{}
+		}
 	}
 	structNames := make(map[string]struct{})
 	for _, struckt := range structs {
@@ -192,6 +195,7 @@ func generate(req *plugin.GenerateRequest, options *opts.Options, enums []Enum,
 		BuildTags:                 options.BuildTags,
 		OmitSqlcVersion:           options.OmitSqlcVersion,
 		WrapErrors:                options.WrapErrors,
+		EmitPointersForNullTypes:  options.EmitPointersForNullTypes,
 	}
 
 	if tctx.UsesCopyFrom && !tctx.SQLDriver.IsPGX() && options.SqlDriver != opts.SQLDriverGoSQLDriverMySQL {
@@ -396,7 +400,8 @@ func filterUnusedStructs(enums []Enum, structs []Struct, queries []Query) ([]Enu
 	for _, enum := range enums {
 		_, keep := keepTypes[enum.Name]
 		_, keepNull := keepTypes["Null"+enum.Name]
-		if keep || keepNull {
+		_, keepPointer := keepTypes["*"+enum.Name]
+		if keep || keepNull || keepPointer {
 			keepEnums = append(keepEnums, enum)
 		}
 	}

internal/codegen/golang/imports.go

@@ -276,7 +276,9 @@ func (i *importer) modelImports() fileImports {
 
 	if len(i.Enums) > 0 {
 		std["fmt"] = struct{}{}
-		std["database/sql/driver"] = struct{}{}
+		if !i.Options.EmitPointersForNullTypes {
+			std["database/sql/driver"] = struct{}{}
+		}
 	}
 
 	return sortedImports(std, pkg)

internal/codegen/golang/mysql_type.go

@@ -13,6 +13,7 @@ func mysqlType(req *plugin.GenerateRequest, options *opts.Options, col *plugin.C
 	columnType := sdk.DataType(col.Type)
 	notNull := col.NotNull || col.IsArray
 	unsigned := col.Unsigned
+	emitPointersForNull := options.EmitPointersForNullTypes
 
 	switch columnType {
 
@@ -127,10 +128,16 @@ func mysqlType(req *plugin.GenerateRequest, options *opts.Options, col *plugin.C
 						}
 						return StructName(schema.Name+"_"+enum.Name, options)
 					} else {
+						var enumTypeName string
 						if schema.Name == req.Catalog.DefaultSchema {
-							return "Null" + StructName(enum.Name, options)
+							enumTypeName = StructName(enum.Name, options)
+						} else {
+							enumTypeName = StructName(schema.Name+"_"+enum.Name, options)
 						}
-						return "Null" + StructName(schema.Name+"_"+enum.Name, options)
+						if emitPointersForNull {
+							return "*" + enumTypeName
+						}
+						return "Null" + enumTypeName
 					}
 				}
 			}

internal/codegen/golang/postgresql_type.go

@@ -577,10 +577,16 @@ func postgresType(req *plugin.GenerateRequest, options *opts.Options, col *plugi
 						}
 						return StructName(schema.Name+"_"+enum.Name, options)
 					} else {
+						var enumTypeName string
 						if schema.Name == req.Catalog.DefaultSchema {
-							return "Null" + StructName(enum.Name, options)
+							enumTypeName = StructName(enum.Name, options)
+						} else {
+							enumTypeName = StructName(schema.Name+"_"+enum.Name, options)
 						}
-						return "Null" + StructName(schema.Name+"_"+enum.Name, options)
+						if emitPointersForNull {
+							return "*" + enumTypeName
+						}
+						return "Null" + enumTypeName
 					}
 				}
 			}

internal/codegen/golang/templates/template.tmpl

@@ -108,6 +108,7 @@ func (e *{{.Name}}) Scan(src interface{}) error {
 	return nil
 }
 
+{{ if not $.EmitPointersForNullTypes }}
 type Null{{.Name}} struct {
 	{{.Name}} {{.Name}} {{if .NameTag}}{{$.Q}}{{.NameTag}}{{$.Q}}{{end}}
   Valid  bool {{if .ValidTag}}{{$.Q}}{{.ValidTag}}{{$.Q}}{{end}} // Valid is true if {{.Name}} is not NULL
@@ -131,6 +132,8 @@ func (ns Null{{.Name}}) Value() (driver.Value, error) {
 	return string(ns.{{.Name}}), nil
 }
 
+{{ end }}
+
 
 {{ if $.EmitEnumValidMethod }}
 func (e {{.Name}}) Valid() bool {

internal/endtoend/testdata/emit_pointers_for_null_types_enum/mysql/go/db.go

@@ -0,0 +1,21 @@
+-- name: GetAll :many
+SELECT * FROM users;
+
+-- name: NewUser :exec
+INSERT INTO users (
+    first_name,
+    last_name,
+    age,
+    shoe_size,
+    shirt_size
+) VALUES
+(?, ?, ?, ?, ?);
+
+-- name: UpdateSizes :exec
+UPDATE users
+SET shoe_size = ?, shirt_size = ?
+WHERE id = ?;
+
+-- name: DeleteBySize :exec
+DELETE FROM users
+WHERE shoe_size = ? AND shirt_size = ?;

internal/endtoend/testdata/emit_pointers_for_null_types_enum/mysql/go/models.go

@@ -0,0 +1,8 @@
+CREATE TABLE users (
+    id integer NOT NULL AUTO_INCREMENT PRIMARY KEY,
+    first_name varchar(255) NOT NULL,
+    last_name varchar(255),
+    age integer NOT NULL,
+    shoe_size ENUM('x-small', 'small', 'medium', 'large', 'x-large') NOT NULL,
+    shirt_size ENUM('x-small', 'small', 'medium', 'large', 'x-large')
+);