graphql-tools-merge-typedefs

This library is used to merge GraphQL query, mutation, and subscription type definitions that are specified in separate files.

Installation

npm install graphql-tools-merge-typedefs

or

yarn add graphql-tools-merge-typedefs

Usage

Imagine the following schema definition file named customer-schema.js:

const { gql } = require('apollo-server');
const customersData = require('./json/customers.json');

exports.typeDefs = gql`
  type Customer {
    id: ID!
    firstName: String!
    lastName: String!
  }

  type Query {
    customer(id: ID!): Customer
  }
`;

exports.resolvers = {
  Query: {
    customer: (obj, args) => customersData.find(customer => customer.id === args.id)
  }
};

And another schema definition file named order-schema.js:

const { gql } = require('apollo-server');
const ordersData = require('./json/orders.json');

const order = gql`
  type Order {
    id: ID!
    product: String!
    quantity: Int!
  }
`;
const query = gql`
  type Query {
    order(id: ID!): Order
  }
`;
// you can also export an array of querys
exports.typeDefs = [ order, query ]

exports.resolvers = {
  Query: {
    order: (obj, args) => ordersData.find(order => order.id === args.id)
  }
};

Merging these two files using the graphql-tools makeExecutableSchema function would result in a merge conflict since both customer-schema.js and order-schema.js files include a "Query" definition. However, using graphql-tools-merge-typedefs, these definitions can be merged as follows:

const { ApolloServer } = require('apollo-server');
const { makeExecutableSchema } = require('graphql-tools');
const { mergeTypeDefs } = require('graphql-tools-merge-typedefs');
const customerSchema = require('./customer-schema');
const orderSchema = require('./order-schema');

// merge conflicting "Query", "Mutation", and "Subscription" definitions
const typeDefs = mergeTypeDefs([
  customerSchema.typeDefs,
  orderSchema.typeDefs
]);

const resolvers = [
  customerSchema.resolvers,
  orderSchema.resolvers
];

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

const server = new ApolloServer({ schema });

server.listen().then(({ url }) => console.log(`Listening on port ${url}`));

If you need to merge typeDefs other than Query, Mutation, and Subscription definitions something you can pass in your own custom type(s) by passing in a string or an array of strings

const gql = require('graphql-tag')
const { mergeTypeDefs } = require('graphql-tools-merge-typedefs');

const typeDefs = mergeTypeDefs([
  customerSchema.typeDefs,
  orderSchema.typeDefs
], 'Local');
...