Invalid JSON is generated with gogo/protobuf's jsonpb.Marshaler

[liranp]

In continue to issue #212, I'm opening a new issue cause they're not necessarily related to each other.

I have changed my gRPC gateway server to use gogo/protobuf's jsonpb.Marshaler instead the one from golang/protobuf. I'm having another issue now; since the change, all JSON messages are marshaled by the jsonpb.Marshaler, but it uses the json field from the protobuf tag instead of the json tag (even if I'm using [(gogoproto.jsontag) = "..."]; which just overrides the json tag if I understood correctly).

Let's say I have the following message in my .proto file:

message Value {
    string foo_bar = 1;
}

In the .pb.go this translated to:

type Value struct {
    FooBar    string     `protobuf:"bytes,2,opt,name=foo_bar,json=fooBar,proto3" json:"foo_bar"`
}

So, the JSON looks like:

{
    "value": {
        "fooBar": "baz"
    }
}

While (at least for my understanding) the expected result is (like it worked before):

{
    "value": {
        "foo_bar": "baz"
    }
}

What am I missing?
Any help will be much appreciated!

[liranp]

I've found the answer, but perhaps we should keep this issue as closed for documentation purposes.

If no WithMarshalerOption is provided to the grpc-gateway's NewServeMux function, it uses a default marshaler which is the jsopb.Marshaler from golang/protobuf, and it instantiates it like this:

defaultMarshaler = &JSONPb{OrigName: true}

So, the solution was just to set OrigName to true as well.

[awalterschulze]

Thanks for providing the answer, this is great :)