Return list from Graphql resolve - react-native

Question

fetchFriends: {
type: new GraphQLList(UserType),
args: {
currentId: { type: new GraphQLNonNull(GraphQLID) }
},
resolve: (_, {currentId}) => {
return Promise.resolve()
.then(() => {
User.findById(currentId, (err, users) => {
users.getFriends((err, user) => {
console.log(user);
return user;
});
});
})
}
/* another version what i tried that returns only the initial findById user
resolve: (_, {currentId}) => {
var value = User.findById(currentId, (err, user) => {
new Promise((resolve, reject) => {
user.getFriends((err, user) => {
console.log('fetch: ', user);
err ? reject(err) : resolve(user)
});
})
})
return value;
}*/
},
I have a graphql resolve that i am getting the User object within the findById callback. that specific object calls getFriends which is a part of a mongoose plugin (friends-of-friends) and the console.log within getFriends callback contains the list in the terminal so i know getFriends
is returning the proper data but i cannot figure out how to return the value into my React-Native Component. i have tried for the past 8 hours everything i can think of and cannot get the value returned out of this function.

Answer 1

You're close, but there's a couple of things to keep in mind when working with resolvers:
Your resolver has to return either a value that matches the type/scalar specified in your schema or a Promise that will resolve to that value.
Mongoose operations can return a promises, and you should utilize this feature of them rather than trying to wrap callbacks inside Promises as this can easily get messy
Return statements inside callbacks at least in this context) don't actually do anything. Return statements inside a then, on the other hand, determine what the promise will resolve to (or what promise to invoke next in the chain).
I would imagine your resolver needs to look something like this:
resolve (_, {currentId}) => {
// calling exec() on the query turns it into a promise
return User.findById(currentId).exec()
// the value the promise resolves to is accessible in the "then" method
.then(user => {
// should make sure user is not null here, something like:
if (!user) return Promise.reject(new Error('no user found with that id'))
// we want the value returned by another async method, getFriends, so
// wrap that call in a promise, and return the promise
return new Promise((resolve, reject) => {
user.getFriends((error, friends) => {
if (error) reject(error)
resolve(friends)
})
})
})
}