[GraphQL] Use GraphQLList with GraphQLObject Types

When working with collections of things in GraphQL, we‘ll always reach out for the GraphQLListType. In this video, we‘ll learn how to use GraphQLList from the graphql package in combination with a GraphQLObject Type to create a field that returns a collection in our Schema.

We can use GraphQLList to fetch list objects:

const queryType = new GraphQLObjectType({
    name: ‘QueryType‘,
    description: ‘The root query type‘,
    fields :{
        videos: {
            type: new GraphQLList(videoType),
            resolve: getVideos
        },
        video: {
            type: videoType,
            args: {
                id: {
                    type : new GraphQLNonNull(GraphQLID),
                    description: ‘The id of the video‘
                }
            },
            resolve: (_, args) => getVideoById(args.id)
        }
    }
});

Data:

const videoA = {
    id: ‘a‘,
    title: ‘Create a GraphQL Schema‘,
    duration: 120,
    watched: true,
};
const videoB = {
    id: ‘b‘,
    title: ‘Ember.js CLI‘,
    duration: 240,
    watched: false,
};
const videos = [videoA, videoB];
const getVideoById = (id) => new Promise((resolve) => {
    const [video] = videos.filter((video) => {
        return video.id === id;
    });

    resolve(video);
});

const getVideos = () => new Promise((resolve) => resolve(videos));

exports.getVideoById = getVideoById;
exports.getVideos = getVideos;