GraphQL + Sequelize resolver giving null data

Question

Technologies in use:

NodeJS to run the http server
ExpressJS framework
Apollo-server-express for graphQL
Sequelize to connect to postgres DB
Postgresql to store data

I am trying to get graphQL working on my node server. Where I am specifically having issues is with the graphql resolver.

I have the following code, which works fine.

let User = require('./server/models').User;
let data = User.find({where: {email: "Test@gmail.com"}})
    .then(function (foundUser) {
            console.log(foundUser.dataValues);
            return foundUser.dataValues;
    });

const resolvers = {
    Query: {
        user(root, args){
            return data;
        }
    }
};

When the client queries the graphql endpoint:

query Query{
  user(email:"literallyanything@cangohereATM.com") {
    email
  }
}

They always get:

{
  "data": {
    "user": {
      "email": "Test@gmail.com"
    }
  }
}

Which is fine! That is the expected behavior. As is, any parameter can get passed into the query with user(email:"literallyanything@cangohereATM.com") and the results will be the same. Again, that's expected.

When I move the code however, so that the request for data from the database is IN the resolver like so:

const resolvers = {
    Query: {
        user(root, args){
            User.find({where: {email: "Test@gmail.com"}})
                .then(function (foundUser) {
                    console.log(foundUser.dataValues);
                    return foundUser.dataValues;
                });
        }
    }
};

the client will always get this as a response from the graphql endpoint using the same query as before (the console.log outputs the appropriate information however):

{
  "data": {
    "user": null
  }
}

I suspect I'm failing to understand how apollo-server-express / graphql-tools handles the promise, but I'm not really sure how to move forward from this point. Any help is much appreciated.

Possible duplicate of [Why does a GraphQL query return null?](https://stackoverflow.com/questions/56319137/why-does-a-graphql-query-return-null) — Daniel Rearden, Jun 02 '19 at 01:56

score 1 · Answer 1 · answered Apr 14 '18 at 12:05

You just need to add a return before User to ensure your Promises are correctly chained.

const resolvers = {
  Query: {
    user(root, args){
      User.find({where: {email: "Test@gmail.com"}})
        .then(function (foundUser) {
          return foundUser.dataValues;
        });
    }
  }
};

In your earlier code (when the call to your model resided outside of the resolver), you were returning data inside of the resolver. In this case, data was not actually your database query result but a Promise that would resolve to that query result. In your updated code, you still have a Promise, but you don't return it inside your resolver function. GraphQL will take the return value and await it if it's a Promise, or otherwise use the value as is -- since you effectively return undefined, that's what the resolver uses for the value of user.

GraphQL + Sequelize resolver giving null data

1 Answers1