Express-graphql: Hooking into the Express response object in the resolver

[erikschlegel]

How do I get access to the express response object within the rootValue resolver method?

i.e.

app.use('/api/messages', graphqlHTTP({
  schema: SpatialMessageSchema,
  rootValue: SpatialMessageResolver,
  graphiql: true,
}));

myResolver(args, res){

[erikschlegel]

@leebyron Is the suggested approach with handling express resolvers to return a Promise?

[leebyron]

Hey Erik,

You can check out the example in https://github.com/graphql/express-graphql#providing-extensions which illustrates using the original response object

For your case of wanting to use request as the rootObject, you could do:

app.use('/api/messages', graphqlHTTP(request => ({
  schema: SpatialMessageSchema,
  rootValue: request,
  graphiql: true,
})));

If you need to do some work before resolving the GraphQL request, then yes you can return a Promise.

app.use('/graphql', graphqlHTTP(request => {
  return doSomethingSlowThenPromise().then(() => ({
    schema: mySchema,
    graphiql: true
  }))
})

You can also always use middleware ahead of the GraphQL middleware:

// some random middleware that takes a minute
app.use('/graphql', (req, res, next) => {
  doSomethingSlowThenCall(value => {
    req.someValue = value;
    // then continue
    next();
  })
});

app.use('/graphql', graphqlHTTP(request => ({
  schema: mySchema,
  rootValue: request.someValue,
  graphiql: true
}))