Swagger-UI query parameters for enum types are sent as strings

[johanbrandhorst]

When using a GET endpoint and an enum type in the query parameter, the swagger definition shows a selection of the string representation of the enum as input options, but using that representation returns an error:

enum MyEnum {
    DEFAULT = 0
    OTHER = 1
}

message Request {
    MyEnum value = 1;
}

service MyService {
    rpc Method(Request) returns (google.protobug.Empty) {
        option (google.api.http) = {
            get: "/api/method"
        };
    };
}

{
  "error": "strconv.ParseInt: parsing \"DEFAULT\": invalid syntax",
  "code": 3
}

The swagger definition needs to use the numeric representation of the enum for it to work.

[tmc]

@johanbrandhorst thanks for the issue report. My preference would be to allow either representation.

[johanbrandhorst]

The error is coming from https://github.com/grpc-ecosystem/grpc-gateway/blob/master/runtime/convert.go#L39.

[johanbrandhorst]

Here's a stack trace (edited):

net/http.(*http2serverConn).runHandler.func1(0xc42031c010, 0xc420471faf, 0xc42034a000)
        /usr/lib/go/src/net/http/h2_bundle.go:4592 +0x190
panic(0x9b54c0, 0xc42012c8a0)
        /usr/lib/go/src/runtime/panic.go:489 +0x2cf
myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime.Int32(0xc4202f45e0, 0x9, 0x0, 0x0, 0x0)
        /go/src/myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/convert.go:41 +0x63
reflect.Value.call(0x9d3b60, 0xab4658, 0x13, 0xa8c513, 0x4, 0xc420471420, 0x1, 0x1, 0xc42012c870, 0x9b54c0, ...)
        /usr/lib/go/src/reflect/value.go:434 +0x91f
reflect.Value.Call(0x9d3b60, 0xab4658, 0x13, 0xc420471420, 0x1, 0x1, 0xa076fc, 0x76, 0x30)
        /usr/lib/go/src/reflect/value.go:302 +0xa4
myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime.populateField(0x9e5400, 0xc4202f2fb0, 0x185, 0xc4202f45e0, 0x9, 0xc420298b40,
 0xc4202f2fb0, 0x185)
        /go/src/myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/query.go:158 +0x21a
myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime.populateFieldValueFromPath(0xda6f40, 0xc4202f2f80, 0xc42012c750, 0x1, 0x1, 0x
c42012c740, 0x1, 0x1, 0xc42012c740, 0x0)
        /go/src/myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/query.go:87 +0x8f7
myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime.PopulateQueryParameters(0xda6f40, 0xc4202f2f80, 0xc4201e4840, 0xf02160, 0xc42
00821a8, 0x433401)
        /go/src/myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/query.go:24 +0x1c3
myrepo/vendor/myprotorepo/myprotoservice.request_Method_0(0x7f11586fa9a0, 0xc4201e4810, 0xdab680, 0xc420253840,
0xdade60, 0xc42000e118, 0xc420342100, 0xc4201e46c0, 0x24, 0x16, ...)
        /go/src/myrepo/vendor/myprotorepo/myprotoservice/myprotoservice.pb.gw.go:193 +0x139
myrepo/vendor/myprotorepo/myprotoservice.RegisteHandler.func7(0xda9740, 0xc42031c010, 0xc420342100, 0xc4201e46c0)
        /go/src/myrepo/vendor/myprotorepo/myprotoservice/myprotoservice.pb.gw.go:490 +0x1fd
myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime.(*ServeMux).ServeHTTP(0xc42024ecf0, 0xda9740, 0xc42031c010, 0xc420342100)
        /go/src/myrepo/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/mux.go:89 +0x7f4
net/http.(*ServeMux).ServeHTTP(0xc420237d40, 0xda9740, 0xc42031c010, 0xc420342100)
        /usr/lib/go/src/net/http/server.go:2238 +0x130

[tmc]

That seems to indicate

grpc-gateway/runtime/query.go

Line 150 in f3aa758

if enumValMap := proto.EnumValueMap(props.Enum); enumValMap != nil {

is failing

[johanbrandhorst]

Indeed EnumValueMap is returning an empty map for the enum type

[johanbrandhorst]

AH this is because we've generated our code with gogo/proto instead of golang/proto, the enum is never registered with golang/proto which is what grpc-gateway calls to. Anything we can do about that?

[johanbrandhorst]

This is probably not grpc-gateways fault, so I'm gonna go ahead and close it. I'm doubtful the grpc-gateway will ever allow the user to specify the protobuf backend.

[chichunhua]

@johanbrandhorst I also face this issue now. Could you tell about how did you fix this?

[johanbrandhorst]

https://jbrandhorst.com/post/gogoproto/ details some of the compatibility issues around using gogo/protobuf (like this one). I would recommend not using gogo/protobuf.

[chichunhua]

Thank you very much for your reply! I’ve read your article and tested with 2 of the options ( option (gogoproto.goproto_registration) = true & WithMarshaler option) but not working yet. It seems like we need all 3 of the options listed in the article. Last one is  add --grpc-gateway_out=allow_patch_feature=false to the protoc command line.

Please let me know if I am wrong.

[chichunhua]

Resolved, thanks a lot! @johanbrandhorst