graphql-ws example: Invalid query returns "Subscriptions should be sent over WebSocket"

[gabubarks]

Since v1.11.0, for some reason invalid queries (for example querying a field on an object that does not exist, or forgetting to add a required argument) always result in a PUSH responses from processRequest if the client has text/event-stream in the accepts header.

But if the server does not actually implement PUSH responses, for example when using websockets for subscriptions and implementing that as in the graphql-ws example:

graphql-helix/examples/graphql-ws/server.ts

Lines 50 to 55 in 3a1c91d

	} else {
	res.status(422);
	res.json({
	errors: [new GraphQLError("Subscriptions should be sent over WebSocket.")],
	});
	}

Then instead of getting a GraphQL validation error you get that "Subscriptions should be sent over WebSocket" message. Notably the version of GraphiQL supplied by graphql-helix has text/event-stream in the accepts header.

My server roughly follows the graphql-ws example, but with some differences like using fastify and having the ws handler in a separate POST-only route, but the issue stems from processRequest returning a PUSH response for GraphQL validation errors when my server does not even implement those otherwise.

To reproduce:

Start the graphql-ws example and execute the (invalid) query in GraphiQL:

mutation { echo(someArgThatDoesNotExist: 1) }

The response will be:

{
  "errors": [
    {
      "message": "Subscriptions should be sent over WebSocket."
    }
  ]
}

Whereas executing the query from a client that only accepts application/json the response will be:

{
    "errors": [
        {
            "locations": [
                {
                    "column": 17,
                    "line": 1
                }
            ],
            "message": "Unknown argument \"someArgThatDoesNotExist\" on field \"Mutation.echo\"."
        }
    ]
}

Is it a bug that GraphQL validation errors are sent by graphql-helix as PUSH responses in the first place?

Or alternatively, is there some option missing in the graphql-ws example to stop the server from sending a PUSH response?

If I implement sendPushResult then obviously the error is correctly returned, but then a client can also query subscriptions over HTTP, which is not my intention.

[n1ru4l]

I just run this example (https://codesandbox.io/s/github/contrawork/graphql-helix/tree/main/examples/express?initialpath=/graphql&file=/server.ts) and followed your instructions. I received the following response, which seems to be correct:

{
  "errors": [
    {
      "message": "Unknown argument \"someArgThatDoesNotExist\" on field \"Mutation.echo\".",
      "locations": [
        {
          "line": 2,
          "column": 8
        }
      ]
    }
  ]
}

Can you provide a reproduction for your setup?

[gabubarks]

Ah, interesting. You're running the express example which does not allow websocket connections and wouldn't have the issue I'm describing, but my issue should occur with the graphql-ws example. And if I try that in the sandbox then you're right, it doesn't seem to occur there either.

I explicitly tested it with the graphql-helix example to make sure it wasn't some issue with my project, and when I tried it before submitting this issue it happened there too.

I will make a minimal reproduction later and post it here. Thanks for checking it!