add casttype support for oneof scalars fields

Makefile

@@ -27,7 +27,7 @@ proto_includes = \
 protos: $(proto_files)
 
 .PHONY: $(proto_files)
-$(proto_files): # tools Makefile
+$(proto_files): tools Makefile
 	# protoc-gen-go
 	protoc \
 		$(proto_includes) \

patch/go.proto

@@ -22,8 +22,8 @@ message Options {
 	optional bool embed = 2;
 
 	// The casstype option changes the generated field type.
-	// All generated code assumes that this type is castable to the protocol buffer field type.
-	// It does not work for structs or enums.
+	// All generated code assumes that this type is castable to the protocol buffer field type,
+	// so it does not work for messages types.
 	// Not supported for repeated fields.
 	optional string casttype = 3;
 

patch/patcher.go

@@ -319,10 +319,13 @@ func (p *Patcher) scanField(f *protogen.Field) {
 	// check casttype
 	if typ := opts.GetCasttype(); typ != "" {
 		switch {
+		case f.Desc.IsList():
+			log.Printf("Warning: casttype declared for repeated field: %s", f.Desc.Name())
 		case f.Message != nil:
 			log.Printf("Warning: casttype declared for message field: %s", f.Desc.Name())
 		case f.Oneof != nil:
-			log.Printf("Warning: casttype for oneof field not supported: %s", f.Desc.Name())
+			p.CastType(ident.WithChild(f.GoIdent, f.GoName), typ)
+			p.CastType(ident.WithChild(m.GoIdent, "Get"+f.GoName), typ)
 		default:
 			p.CastType(ident.WithChild(m.GoIdent, f.GoName), typ)
 			p.CastType(ident.WithChild(m.GoIdent, "Get"+f.GoName), typ)

tests/message/message.extensions.go

@@ -12,6 +12,6 @@ type Float float32
 
 type Double float64
 
-type UInt32 uint32
+type Uint32 uint32
 
-type UInt64 uint64
+type Uint64 uint64

tests/message/message_casttypes.proto

@@ -14,6 +14,13 @@ message MessageWithCustomTypes {
   int64 int64_field = 3 [(go.field).casttype = "Int64"];
   float float_field = 4 [(go.field).casttype = "Float"];
   double double_field = 5 [(go.field).casttype = "Double"];
-  uint32 uint32_field = 6 [(go.field).casttype = "UInt32"];
-  uint64 uint64_field = 7 [(go.field).casttype = "UInt64"];
+  uint32 uint32_field = 6 [(go.field).casttype = "Uint32"];
+  uint64 uint64_field = 7 [(go.field).casttype = "Uint64"];
+}
+
+message MessageWithOneOfCustomType {
+  oneof one_of {
+    string string_field = 1 [(go.field).casttype = "String"];
+    int64 int64_field = 3 [(go.field).casttype = "Int64"];
+  }
 }

tests/message/message_test.go

@@ -3,6 +3,7 @@ package message
 import (
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"google.golang.org/protobuf/proto"
 
 	"github.com/alta/protopatch/tests"
@@ -128,4 +129,12 @@ func TestMessageWithCustomTypes(t *testing.T) {
 	var _ float64 = float64(m.DoubleField)
 	var _ uint32 = uint32(m.Uint32Field)
 	var _ uint64 = uint64(m.Uint64Field)
+
+	assert.Equal(t, String("42"), m.StringField)
+	assert.Equal(t, Int32(42), m.Int32Field)
+	assert.Equal(t, Int64(42), m.Int64Field)
+	assert.Equal(t, Float(42), m.FloatField)
+	assert.Equal(t, Double(42), m.DoubleField)
+	assert.Equal(t, Uint32(42), m.Uint32Field)
+	assert.Equal(t, Uint64(42), m.Uint64Field)
 }