refactor: support proto2 optional

integration/simple-proto2/simple.proto

@@ -8,4 +8,5 @@ enum EnumWithoutZero {
 
 message Issue56 {
   required EnumWithoutZero test = 1;
+  optional int32 foo = 2;
 }

integration/simple-proto2/simple.ts

@@ -1,12 +1,15 @@
+/* eslint-disable */
 import { Writer, Reader } from 'protobufjs/minimal';
 
 
 export interface Issue56 {
   test: EnumWithoutZero;
+  foo?: number;
 }
 
 const baseIssue56: object = {
   test: 1,
+  foo: 0,
 };
 
 export const protobufPackage = 'simple'
@@ -46,6 +49,9 @@ export function enumWithoutZeroToJSON(object: EnumWithoutZero): string {
 export const Issue56 = {
   encode(message: Issue56, writer: Writer = Writer.create()): Writer {
     writer.uint32(8).int32(message.test);
+    if (message.foo !== undefined) {
+      writer.uint32(16).int32(message.foo);
+    }
     return writer;
   },
   decode(input: Uint8Array | Reader, length?: number): Issue56 {
@@ -58,6 +64,9 @@ export const Issue56 = {
         case 1:
           message.test = reader.int32() as any;
           break;
+        case 2:
+          message.foo = reader.int32();
+          break;
         default:
           reader.skipType(tag & 7);
           break;
@@ -72,6 +81,9 @@ export const Issue56 = {
     } else {
       message.test = 1;
     }
+    if (object.foo !== undefined && object.foo !== null) {
+      message.foo = Number(object.foo);
+    }
     return message;
   },
   fromPartial(object: DeepPartial<Issue56>): Issue56 {
@@ -81,11 +93,15 @@ export const Issue56 = {
     } else {
       message.test = 1;
     }
+    if (object.foo !== undefined && object.foo !== null) {
+      message.foo = object.foo;
+    }
     return message;
   },
   toJSON(message: Issue56): unknown {
     const obj: any = {};
     message.test !== undefined && (obj.test = enumWithoutZeroToJSON(message.test));
+    message.foo !== undefined && (obj.foo = message.foo);
     return obj;
   },
 };

src/main.ts

@@ -482,7 +482,11 @@ function generateEnumToJson(fullName: string, enumDesc: EnumDescriptorProto): Fu
 
 // When useOptionals=true, non-scalar fields are translated into optional properties.
 function isOptionalProperty(field: FieldDescriptorProto, options: Options): boolean {
-  return (options.useOptionals && isMessage(field) && !isRepeated(field)) || field.proto3Optional;
+  return (
+    (options.useOptionals && isMessage(field) && !isRepeated(field)) ||
+    field.proto3Optional ||
+    field.label === FieldDescriptorProto.Label.LABEL_OPTIONAL
+  );
 }
 
 // Create the interface with properties
@@ -847,6 +851,11 @@ function generateEncode(
         )
         .addStatement('%L', writeSnippet(`message.${fieldName}`))
         .endControlFlow();
+    } else if (field.label === FieldDescriptorProto.Label.LABEL_OPTIONAL) {
+      func = func
+        .beginControlFlow('if (message.%L !== undefined)', fieldName)
+        .addStatement('%L', writeSnippet(`message.${fieldName}`))
+        .endControlFlow();
     } else {
       func = func.addStatement('%L', writeSnippet(`message.${fieldName}`));
     }
@@ -979,7 +988,9 @@ function generateFromJson(
     if (
       !isRepeated(field) &&
       field.type !== FieldDescriptorProto.Type.TYPE_BYTES &&
-      options.oneof !== OneofOption.UNIONS
+      options.oneof !== OneofOption.UNIONS &&
+      !field.proto3Optional &&
+      field.label !== FieldDescriptorProto.Label.LABEL_OPTIONAL
     ) {
       func = func.nextControlFlow('else');
       func = func.addStatement(
@@ -1208,7 +1219,12 @@ function generateFromPartial(
       }
     }
 
-    if (!isRepeated(field) && options.oneof !== OneofOption.UNIONS) {
+    if (
+      !isRepeated(field) &&
+      options.oneof !== OneofOption.UNIONS &&
+      !field.proto3Optional &&
+      field.label !== FieldDescriptorProto.Label.LABEL_OPTIONAL
+    ) {
       func = func.nextControlFlow('else');
       func = func.addStatement(
         `message.%L = %L`,

src/types.ts

@@ -377,7 +377,7 @@ export function toTypeName(
   field: FieldDescriptorProto,
   options: Options
 ): TypeName {
-  let type = basicTypeName(typeMap, field, options, { keepValueType: false });
+  let type = basicTypeName(typeMap, field, options, { keepValueType: true });
   if (isRepeated(field)) {
     const mapType = detectMapType(typeMap, messageDesc, field, options);
     if (mapType) {
@@ -404,7 +404,10 @@ export function toTypeName(
   // clause, spelling each option out inside a large type union. No need for
   // union with `undefined` here, either.
   if (
-    (!isWithinOneOf(field) && isMessage(field) && !options.useOptionals) ||
+    (!isWithinOneOf(field) &&
+      isMessage(field) &&
+      !options.useOptionals &&
+      field.label !== FieldDescriptorProto.Label.LABEL_REQUIRED) ||
     (isWithinOneOf(field) && options.oneof === OneofOption.PROPERTIES) ||
     (isWithinOneOf(field) && field.proto3Optional)
   ) {