relay: commitMutation should return errors in onCompleted

Hi, I’m trying to propagate errors to the users that occurred in a commitMutation The following documentation does not really provide any info other that an array is returned in the onCompleted callback #commitMutation.

Giving the code example, errors are undefind if an error occur on the server. I’m using a wrong id on purpose (for testing) and the graphql server throws an error.

  const mutation = ... 

  const deleteStuff = (environment, { stuffId }) => {
    const variables = {
      input: { stuffId }
    };
  
    commitMutation(environment, {
      mutation,
      variables,
      onCompleted: (response, errors) => {
        console.log("response", response)
        console.log("errors", errors)
      },
      onError: err => console.error("ERR", err)
    });
  };

Ok, so onError shows on errors, thats fine. But errors are undefind in onCompled. Is this expected behaviour?

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 18 (8 by maintainers)

Most upvoted comments

We are already dealing with Relays lack of implementing the GraphQL standard

Just to be clear, Relay does conform to the GraphQL spec and best practices - but I can understand confusion here, as the best practices for error handling in GraphQL have emerged over time. The GraphQL errors field is intended for truly exceptional errors such as an invalid query or variable value: things that are not reasonably expected to occur in an application. Invalid user input or a backend service being unavailable are reasonable errors that are expected to occur (hopefully infrequently for the service down case!). If information about errors is required by the application to function, I suggest following @leebyron’s advice:

GraphQL errors encode exceptional scenarios - like a service being down or some other internal failure. Errors which are part of the API domain should be captured within that domain.

link

a common best practice has been to include user errors as part of the schema itself so they can contain domain specific information.

link

There’s a great writeup by @alloy on this approach as the final suggestion in http://artsy.github.io/blog/2018/10/19/where-art-thou-my-error/#Make.exceptions.first-class.citizens.of.your.schema.

josephsavona on Feb 6, 2019