Field \"me\" of type \"User\" must have a selection of subfields

Question

Hi I am trying to learn GraphQL language. I have below snippet of code.

// Welcome to Launchpad! // Log in to edit and save pads, run queries in GraphiQL on the right. // Click "Download" above to get a zip with a standalone Node.js server. // See docs and examples at https://github.com/apollographql/awesome-launchpad  // graphql-tools combines a schema string with resolvers. import { makeExecutableSchema } from 'graphql-tools';  // Construct a schema, using GraphQL schema language const typeDefs = `     type User {         name: String!         age: Int!     }      type Query {         me: User     } `;  const user = { name: 'Williams', age: 26};  // Provide resolver functions for your schema fields const resolvers = {   Query: {     me: (root, args, context) => {       return user;     },   }, };  // Required: Export the GraphQL.js schema object as "schema" export const schema = makeExecutableSchema({   typeDefs,   resolvers, });  // Optional: Export a function to get context from the request. It accepts two // parameters - headers (lowercased http headers) and secrets (secrets defined // in secrets section). It must return an object (or a promise resolving to it). export function context(headers, secrets) {   return {     headers,     secrets,   }; };  // Optional: Export a root value to be passed during execution // export const rootValue = {};  // Optional: Export a root function, that returns root to be passed // during execution, accepting headers and secrets. It can return a // promise. rootFunction takes precedence over rootValue. // export function rootFunction(headers, secrets) { //   return { //     headers, //     secrets, //   }; // }; 

Request:

{   me } 

Response:

{   "errors": [     {       "message": "Field \"me\" of type \"User\" must have a selection of subfields. Did you mean \"me { ... }\"?",       "locations": [         {           "line": 4,           "column": 3         }       ]     }   ] } 

Does anyone know what I am doing wrong ? How to fix it ?

Answer 1

From the docs:

A GraphQL object type has a name and fields, but at some point those fields have to resolve to some concrete data. That's where the scalar types come in: they represent the leaves of the query.

GraphQL requires that you construct your queries in a way that only returns concrete data. Each field has to ultimately resolve to one or more scalars (or enums). That means you cannot just request a field that resolves to a type without also indicating which fields of that type you want to get back.

That's what the error message you received is telling you -- you requested a User type, but you didn't tell GraphQL at least one field to get back from that type.

To fix it, just change your request to include name like this:

{   me {     name   } } 

... or age. Or both. You cannot, however, request a specific type and expect GraphQL to provide all the fields for it -- you will always have to provide a selection (one or more) of fields for that type.