GraphQL-tools: generate and mock GraphQL.js schemas

This package allows you to use the GraphQL schema language to build your GraphQL.js schema, and also includes useful schema tools like per-type mocking.

Documentation

Read the docs.

Example

The "Hello World" server which powers our client examples is a great place to start if you're looking for a minimal codebase powered by graphql-tools.

When using graphql-tools, you describe the schema as a GraphQL type language string:

const schema = `
type Author {
  id: Int! # the ! means that every author object _must_ have an id
  firstName: String
  lastName: String
  posts: [Post] # the list of Posts by this author
}

type Post {
  id: Int!
  title: String
  author: Author
  votes: Int
}

# the schema allows the following query:
type Query {
  posts: [Post]
}

# this schema allows the following mutation:
type Mutation {
  upvotePost (
    postId: Int!
  ): Post
}

# we need to tell the server which types represent the root query
# and root mutation types. We call them RootQuery and RootMutation by convention.
schema {
  query: Query
  mutation: Mutation
}
`;

export default schema;

Then you define resolvers as a nested object that maps type and field names to resolver functions:

const resolverMap = {
  Query: {
    posts() {
      return posts;
    },
  },
  Mutation: {
    upvotePost(_, { postId }) {
      const post = find(posts, { id: postId });
      if (!post) {
        throw new Error(`Couldn't find post with id ${postId}`);
      }
      post.votes += 1;
      return post;
    },
  },
  Author: {
    posts(author) {
      return filter(posts, { authorId: author.id });
    },
  },
  Post: {
    author(post) {
      return find(authors, { id: post.authorId });
    },
  },
};

export default resolverMap;

At the end, the schema and resolvers are combined using makeExecutableSchema:

import schema from './data/schema.js';
import resolverMap from './data/resolvers';

const executableSchema = makeExecutableSchema({
  typeDefs: schema,
  resolvers: resolverMap,
});

This example has the entire type definition in one string and all resolvers in one object, but you can combine types and resolvers from multiple files, as documented in the modularizing the schema section of the docs.

Contributions

Contributions, issues and feature requests are very welcome. If you are using this package and fixed a bug for yourself, please consider submitting a PR!