Compile protobuf to use Java primitive classes instead of well-known types

[Renatas M]

Lets say I have test.proto file:

    syntax = "proto3";
   
    option java_package = "testing";
    option java_outer_classname = "Test_v1";
   
    import "google/protobuf/wrappers.proto";
   
    message TestMessage {
        .google.protobuf.Int32Value integerField = 1;
    }

If I compile (using protoc v3.5.0) it to c# code I will get nullable type properties:

    public int? IntegerField {
       get { return integerField_; }
       set { integerField_ = value; }
     }

But if I compile it to Java code, fields will be of well-known type:

    public Builder setIntegerField(com.google.protobuf.Int32Value value) {
      if (integerFieldBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        integerField_ = value;
        onChanged();
      } else {
        integerFieldBuilder_.setMessage(value);
     }

I am moving project from proto2 to proto3 so I would like to avoid using well-known types, because it will require a lot of work to change related code. With c# projects I will not require to modify anything but in Java I will need to do as in the following example: 

    TestMessage.Builder builder = TestMessage.newBuilder();
    builder.setIntegerField(5); //<-- instead of this (with proto2)
    builder.setIntegerField(Int32Value.newBuilder().setValue(5)); //<-- I will need to change to something like this (with proto3)

Is there a way to compile proto file to Java so setters would accept primitive classes/wrappers (String, Integer, etc.) as parameters?

[Josh Humphries]

What you're asking for is not currently do-able. There is an existing request to add this functionality though: https://github.com/google/protobuf/issues/2055

In the meantime, you can accomplish this using a custom plugin that is run in addition to the normal java code-gen. Plugins can generate extra code into existing Java source files using insertion points. So you could generate overloaded forms of the setter methods into the relevant builder classes (via "builder_scope" insertion points).

----
Josh Humphries
jh...@bluegosling.com

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[Renatas M]

Hi Josh, 

thank you a lot for informative answer.

----
Josh Humphries
jh...@bluegosling.com

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