protoc-gen-swagger map type filed doesn't support options.openapiv2_field

[yangxikun]

🐛 Bug Report

message GetSubjectPermissions2DReply{
  map<string, ListOfString> permissions = 1 [(grpc.gateway.protoc_gen_swagger.options.openapiv2_field) = {title: "展开的二级权限列表", description:"展开的二级权限列表"}];
}

generated swagger json:

    "HodorGetSubjectPermissions2DReply": {
      "type": "object",
      "properties": {
        "permissions": {
          "type": "object",
          "additionalProperties": {
            "$ref": "#/definitions/HodorListOfString"
          }
        }
      },
      "title": "GetSubjectPermissions2DReply"
    },

permissions.title and permissions.description is not set.

Your Environment

grpc-gateway v1.14.6

Other Info

I dig into the source code of protoc-gen-swagger, found the problem is in template.go:schemaOfField：

// schemaOfField returns a swagger Schema Object for a protobuf field.
func schemaOfField(f *descriptor.Field, reg *descriptor.Registry, refs refMap) swaggerSchemaObject {
	const (
		singular = 0
		array    = 1
		object   = 2
	)
	var (
		core      schemaCore
		aggregate int
	)

	fd := f.FieldDescriptorProto
	if m, err := reg.LookupMsg("", f.GetTypeName()); err == nil {
		if opt := m.GetOptions(); opt != nil && opt.MapEntry != nil && *opt.MapEntry {
			fd = m.GetField()[1]
			aggregate = object
		}
	}
	if fd.GetLabel() == pbdescriptor.FieldDescriptorProto_LABEL_REPEATED {
		aggregate = array
	}
        ……
}

When the field is map type, fd = m.GetField()[1] use the value's FieldDescriptorProto. Because the mapentry is auto generate, so the fd.Options is always nil.

[johanbrandhorst]

Hi, thanks for the bug report. Really nice work debugging this, would you be willing to submit a fix? I'd start by adding a failing test, and then try and modify the code.

[yangxikun]

@johanbrandhorst The master branch can reproduce this bug, I will submit a PR in the next few days.