Support oneof types of fields

[yugui]

Extracted from #5.

Currently oneof fields are not supported. They should be allowed in request body and query string as well as other types.

• This feature requires allow use of jsonpb for marshaling #79 because "encoding/json".Marshal returns error for oneof fields
• No plan to allow them in path parameters because path parameters are "mandatory" parameters. So they don't fit to oneof very well.

[johansja]

Use of https://godoc.org/github.com/golang/protobuf/jsonpb instead of encoding/json can help.

[yugui]

@johansja Thank you. Yes, it is #79.

[gyuho]

@yugui etcd is hitting this issue, though it's happening only in experimental feature.

Do we have any workaround for this? Or ETA to support this?

Thanks!

[johansja]

You should be able to use one_of with the help of runtime.WithMarshalerOption.

[yugui]

Now the default marshaller uses 'jsonpb'. So I think it is supported.

• https://github.com/gengo/grpc-gateway/blob/master/examples/browser/a_bit_of_everything_service.spec.js#L81
• https://travis-ci.org/gengo/grpc-gateway/jobs/137727616#L1049

@gyuho Could you re-confirm with the HEAD of the master branch?
Let me know if you still have the issue.
I'll close this issue if otherwise.

[gyuho]

@yugui First thanks for helping debug this.

etcd still complains {"Error":"json: cannot unmarshal object into Go value of type etcdserverpb.isWatchRequest_RequestUnion","Code":2}. And tried the latest master branch of grpc-gateway and golang/protobuf, and regenerate the gateway files, as here etcd-io/etcd@8759230.

I added reflect.TypeOf(marshaler) to this line https://github.com/gyuho/etcd/blob/3108859828f851e9a46772fe8e16d257b40f3639/etcdserver/etcdserverpb/rpc.pb.gw.go#L91 and confirm that *runtime.JSONPb typed marshaler is being used, but still seeting that error.

*runtime.JSONPb
2016-07-06 22:07:13.861689 I | v3rpc/grpc: Failed to decode request: json: cannot unmarshal object into Go value of type etcdserverpb.isWatchRequest_RequestUnion

Maybe we generate gateway files in the wrong way? I tried to regenerate *.gw.go files but don't see any diff.

Thanks.

[yugui]

@gyuho I see. I'll take a look.

[yugui]

@gyuho
Does this work fine?

curl -L http://localhost:2379/v3alpha/watch -X POST -d '{"create_request": {"key": "Zm9v"}}'

You need to specify literally one of the fields grouped by request_union.

[gyuho]

@yugui Still doesn't seem to work.

curl -L http://localhost:2379/v3alpha/watch -X POST -d '{"create_request": {"key": "Zm9v"}}'

{"Error":"unknown field \"create_request\" in etcdserverpb.WatchRequest","Code":2}

Thanks!

[yugui]

@gyuho
It does not look to be an issue of grpc-gateway. I could reproduce the issue without grpc-gateway.

package main

import (
        "log"

        "github.com/coreos/etcd/etcdserver/etcdserverpb"
        "github.com/golang/protobuf/jsonpb"
)

func main() {
        const input = `{"create_request": {"key": "Zm9v"}}`
        var protoReq etcdserverpb.WatchRequest
        if err := jsonpb.UnmarshalString(input, &protoReq); err != nil {
                log.Fatal(err)
        }
}

$ go run main.go
2016/07/12 12:15:28 unknown field "create_request" in etcdserverpb.WatchRequest
exit status 1

I don't know what the root cause actually is, but I suspect incompatibility between github.com/golang/protobuf/jsonpb and gogoproto.

[yugui]

@gyuho Confirmed in https://gist.github.com/yugui/4425e705680fb4f6c99423b99b8a83d2

$ go get gist.github.com/4425e705680fb4f6c99423b99b8a83d2.git
$ go build -o test gist.github.com/4425e705680fb4f6c99423b99b8a83d2.git
$ ./test
$ echo $?
0
$ go build --tags=gogo -o test gist.github.com/4425e705680fb4f6c99423b99b8a83d2.git
$ ./test
2016/07/12 12:53:05 unknown field "create_request" in main.WatchRequest
$ echo $?
1

[gyuho]

@yugui I will see if I can find some workarounds or file an issue to gogoproto. Thanks a lot!

[yugui]

@gyuho
I am not yet confident but I suspect if this proto in (*WatchRequest).XXX_OneofFuncs,

func (*WatchRequest) XXX_OneofFuncs() (func(msg proto.Message, b *proto.Buffer) error, func(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error), func(msg proto.Message) (n int), []interface{}) {

at https://github.com/gyuho/etcd/blob/3108859828f851e9a46772fe8e16d257b40f3639/etcdserver/etcdserverpb/rpc.pb.go#L1084
should have been github.com/golang/protobuf/proto but not github.com/gogo/protobuf/proto so that it is compatible to https://github.com/golang/protobuf/blob/ba6f978a1a6606adf3ccb6987f15c64262bfdbc2/proto/properties.go#L729.