gRPC HTTP body mapping works incorrectly

[chebykinn]

Hi, I've noticed some inconsistency with grpc http transcoding.

Here's how to reproduce it:

1. Take example proto schema from google doc (https://cloud.google.com/endpoints/docs/grpc/transcoding#map_a_create_method)
   Full schema:

syntax = "proto3";

package shelf;

import "github.com/metaverse/truss/deftree/googlethirdparty/annotations.proto";

service Shelfs {

  // Creates a new shelf in the bookstore.
  rpc CreateShelf(CreateShelfRequest) returns (Shelf) {
    // Client example:
    //   curl -d '{"theme":"Music"}' http://DOMAIN_NAME/v1/shelves
    option (google.api.http) = {
      post: "/v1/shelves"
      body: "shelf"
    };
  }
}

// Request message for CreateShelf method.
message CreateShelfRequest {
  // The shelf resource to create.
  Shelf shelf = 1;
}

// A shelf resource.
message Shelf {
  // A unique shelf id.
  int64 id = 1;
  // A theme of the shelf (fiction, poetry, etc).
  string theme = 2;
}

2. Generate and run server
3. Add debug printing of Shelf field to CreateShelf:

func (s shelfsService) CreateShelf(ctx context.Context, in *pb.CreateShelfRequest) (*pb.Shelf, error) {
	fmt.Printf("in: %v\n", in.Shelf)
	var resp pb.Shelf
	return &resp, nil
}

4. Make curl request as suggested in the example: curl -d '{"theme":"Music"}' 'http://localhost:5050/v1/shelves'
   The server does not set the Shelf field:

2021/02/07 00:16:57 transport gRPC addr :5040
2021/02/07 00:16:57 transport debug addr :5060
2021/02/07 00:16:57 transport HTTP addr :5050
in: <nil>

If you wrap the body with the shelf object, like curl -d '{"shelf": {"theme":"Music"}}' 'http://localhost:5050/v1/shelves'
the field will be correctly set to theme:"Music"

[chebykinn]

Just noticed that wildcard mapping does not work as intended as well:

    option (google.api.http) = {
      post: "/v1/shelves/{shelf_id}"
      body: "*"
    };

Still have to send the body with nested object: '{"shelf": {"theme":"Music"}}'

UPD: Nevermind, this is working fine.

[zaquestion]

interesting, ive never looked that closely at how the mapping is supposed to function, it seems like there is a mismatch in what truss does and the spec.

The wildcard case i would expect to need to be wrapped too? youre saying this allowed you to remove the outer "shelf" json?

@adamryman can you shed any insight on this and advise on fixing?

[chebykinn]

No, the wildcard should take the whole request body as is, except fields that are mapped in the request path, so in this case "shelf" object should not be removed.