Graphql-tools: Chaining local and remote resolvers?

[adamkl]

I’m investigating a scenario where we proxy a remote GraphQL API, extend the types, and transform the data as it passes through.

Extending the types and merging the local schema/resolvers isn’t a problem, but I’m stuck when it comes to transforming the data as it passes through.

It seems like I can override the delegating resolver with a local one, but I can’t let the delegating resolver execute, and then pass the results into a local resolver to alter the data.

Is this even possible with the current mergeSchema and makeRemoteExecutableSchema? Or am I going to have to get my hands a little dirty.

[adamkl]

Could I use a custom ApolloLink for this?

const postProcessingLink = new ApolloLink((operation, forward) => {
  return forward(operation).map((data) => {
    return graphql(
      schema: postProcessingSchema,
      requestString: operation.query,
      rootValue: data,
      variableValues: operation.variables,
      operationName: operation.operationName
    );
  })
});

Is this a reasonable idea to explore?

[adamkl]

So I'm just going to answer my own issue here in case this helps anyone else.

I was able to accomplish this with a post processing ApolloLink as suggested above. Here is a gist of how I did it.

I hope this is useful to someone else.

[hwillson]

Your approach makes sense to me @adamkl - thanks for sharing!