Should I be using a list (array) here in GraphQL?

Question

[Previously titled "How to get 1 record from a list..."]

I am very new to GraphQL and trying to understand how to get 1 record from query.

This is the result of my current query:

{
    "data": {
        "todos": null
    }
}

I am not sure what is wrong. I would like the result to be this:

{
    "data": {
        "todos": {
            "id": 1,
            "title": "wake up",
            "completed": true
        }
    }
}

Here is my code that I've created as I try to learn GraphQL.

schema.js:

var graphql = require('graphql');

var TODOs = [
  {
    "id": 1,
    "title": "wake up",
    "completed": true
  },
  {
    "id": 2,
    "title": "Eat Breakfast",
    "completed": true
  },
  {
    "id": 3,
    "title": "Go to school",
    "completed": false
  }
];

var TodoType = new graphql.GraphQLObjectType({
  name: 'todo',
  fields: function () {
    return {
      id: {
        type: graphql.GraphQLID
      },
      title: {
        type: graphql.GraphQLString
      },
      completed: {
        type: graphql.GraphQLBoolean
      }
    };
  }
});

var queryType = new graphql.GraphQLObjectType({
  name: 'Query',
  fields: function () {
    return {
      todos: {
        type: new graphql.GraphQLList(TodoType),
        args: {
          id: { type: graphql.GraphQLID }
        },
      resolve: function (source, args, root, ast) {
        if (args.id) {
          return TODOs.filter(function(item) {
            return item.id === args.id;
            })[0];
          }

          return TODOs;
        }
      }
    }
  }
});

module.exports = new graphql.GraphQLSchema({
  query: queryType
});

index.js:

var graphql = require ('graphql').graphql;
var express = require('express');
var graphQLHTTP = require('express-graphql');
var Schema = require('./schema');

var query = 'query { todos(id: 1) { id, title, completed } }';
graphql(Schema, query).then( function(result) {
  console.log(JSON.stringify(result,null," "));
});

var app = express()
  .use('/', graphQLHTTP({ schema: Schema, pretty: true }))
  .listen(8080, function (err) {
    console.log('GraphQL Server is now running on localhost:8080');
});

To run this code I just run node index from the root directory. How can I get one specific record returned by the records id?

helfer · Accepted Answer · 2016-06-23 03:13:34Z

4

You have the wrong type for the todos field of your queryType. It should be TodoType, not a list of TodoType. You're getting an error because GraphQL expects to see a list, but your resolver is just returning a single value.

By the way, I suggest passing the graphiql: true option to graphqlHTTP, which will let you use GraphiQL to explore your schema and make queries.

answered Jun 23, 2016 at 3:13

helfer

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2 Comments

Mdd Over a year ago

Thanks! Is it typical to create different fields for lists and for a single value in the list? For instance a todos field with a resolver that returns a list, and a todo field with a resolver that returns a single item from the list?

stubailo Over a year ago

Yes, in general if you want something to return different types of data, you need to declare different fields for it. This way, you can be sure that the same query always returns the same shape of data, even if the arguments are different.

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