[BUG][Golang][Client] composed-OneOf become undefined

[zigen]

Description

composed-oneOf generates undefined type OneOfObjA.
here is generated code
this api should return one of ObjA or ObjB.
but Golang doesn't have such feature to describe TypeA | TypeB.

FYI https://developers.google.com/protocol-buffers/docs/reference/go-generated#oneof

openapi-generator version

4.0.0-SNAPSHOT 9e1cce2e7

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/test/resources/3_0/composed-oneof.yaml

Command line used for generation

generate -t modules/openapi-generator/src/main/resources/go -i modules/openapi-generator/src/test/resources/3_0/composed-oneof.yaml -g go -o $GOPATH/src/github.com/zigen/go-sample-api -DpackageName=go_sample_api
https://github.com/zigen/openapi-generator-go-client-oas3-repro/blob/master/go-oneof.sh

Steps to reproduce

generate spec modules/openapi-generator/src/test/resources/3_0/composed-oneof.yam to golang and import it.

this repo includes steps to repro, generated conde and example client.
https://github.com/zigen/openapi-generator-go-client-oas3-repro

Related issues/PRs

#1360
#500

Suggest a fix

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[wing328]

@zigen thanks for opening an issue. I wonder how Go GRPC client handles "oneOf" and potentially we can reuse similar code if the license permits so that we don't need to reinvent the wheel.

[zigen]

hmm, it looks here? https://github.com/golang/protobuf/blob/master/protoc-gen-go/generator/generator.go#L2246
it's complecated and they don't use template.

protoc and protoc-gen-go written in Go, so I think it's hard to reuse it in this project.
And the license is BSD-3-Clause https://github.com/golang/protobuf/blob/master/LICENSE

I will try to investigate protoc-gen-go and implement in this year end.

[zigen]

FYI
proto :

message Request {
  oneof length {
    int32 short = 3;
    int64 long = 4;
  }
}

part of generated output with $ protoc api.proto --go_out=./ :

type isRequest_Length interface {
	isRequest_Length()
}

type Request_Short struct {
	Short int32 `protobuf:"varint,3,opt,name=short,proto3,oneof"`
}

type Request_Long struct {
	Long int64 `protobuf:"varint,4,opt,name=long,proto3,oneof"`
}

protoc-gen-go generates with field tag oneof , and go proto lib parse it.
https://github.com/golang/protobuf/blob/master/proto/properties.go#L247
https://github.com/golang/protobuf/blob/master/proto/properties.go#L375
https://github.com/golang/protobuf/blob/master/proto/text_parser.go#L582

[geoah]

I'm seeing the same issue in both 4.2.2-SNAPSHOT (70954ca) and 5.0.x (7f05cf0).
Are there any plans or ideas on how to fix this?

[emil14]

any updates on this one?