GraphQL Nested Queries

The whole point of GraphQL is its flexibility, I can view all the authors in the database and then I can add an additional query that can display all the books by the one author, we call these nested queries. I recently spent an afternoon + evening with @manekenpix to take a look at nested queries in GraphQL for the Telescope project.

We currently have a schema like below

  # 'Feed' matches our Feed type used with redis
  type Feed {
    id: String
    author: String
    url: String
    posts: [Post]
  }  # 'Post' matches our Post type used with redis
  type Post {
    id: String
    author: String
    title: String
    html: String
    text: String
    published: String
    updated: String
    url: String
    site: String
    guid: String
  }

Notice feed can also return an array of Post,  to allow nested queries, we have to define them in resolvers after the Query:

module.exports.resolvers = {
  Query: {
    //Queries are here
  },
  Feed: {
    posts: async parent => {
      const maxPosts = await getPostsCount();
      const ids = await getPosts(0, maxPosts);
      const posts = await Promise.all(ids.map(postId => getPost(postId)));
      const filteredPosts = posts.filter(post => post.author === parent.author);
      return filteredPosts;
    },
  },
};

What the above code does is get all Posts in the database, then filter the Posts only returning Posts that have the same author as the returned value of the feed author. For example if I'm running the following query in GraphQL

{
  getFeedById(id: "123") {
    author
    id
    posts {
      title
    }
  }
}

and the author name is Marie, the parent parameter that is provided to the nested query (posts) will be the results of the getFeedById which in this case the author name is Marie.

Real life data using a classmate of mine: