apollo-server-express

What is apollo-server-express?

The apollo-server-express package is a library that allows you to integrate Apollo Server with an Express application. It provides tools to build a GraphQL server with Express, enabling you to define your GraphQL schema, resolvers, and context, and to handle HTTP requests and responses.

What are apollo-server-express's main functionalities?

Setting up a basic Apollo Server with Express

This code sets up a basic Apollo Server with Express. It defines a simple GraphQL schema with a single query and a resolver for that query. The Apollo Server is then applied as middleware to the Express app, and the server is started on port 4000.

const express = require('express');
const { ApolloServer, gql } = require('apollo-server-express');

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!',
  },
};

const server = new ApolloServer({ typeDefs, resolvers });
const app = express();
server.applyMiddleware({ app });

app.listen({ port: 4000 }, () =>
  console.log(`Server ready at http://localhost:4000${server.graphqlPath}`)
);

Adding context to Apollo Server

This code demonstrates how to add context to the Apollo Server. The context function extracts the user from the request headers and makes it available to the resolvers. The resolver for the 'hello' query uses the context to personalize the response.

const express = require('express');
const { ApolloServer, gql } = require('apollo-server-express');

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: (parent, args, context) => `Hello ${context.user}!`,
  },
};

const server = new ApolloServer({ 
  typeDefs, 
  resolvers, 
  context: ({ req }) => ({ user: req.headers.user || 'world' }) 
});
const app = express();
server.applyMiddleware({ app });

app.listen({ port: 4000 }, () =>
  console.log(`Server ready at http://localhost:4000${server.graphqlPath}`)
);

Using Apollo Server with Express middleware

This code shows how to use Apollo Server with other Express middleware. In this example, the body-parser middleware is used to parse JSON request bodies before the Apollo Server middleware is applied.

const express = require('express');
const { ApolloServer, gql } = require('apollo-server-express');
const bodyParser = require('body-parser');

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!',
  },
};

const server = new ApolloServer({ typeDefs, resolvers });
const app = express();

app.use(bodyParser.json());
server.applyMiddleware({ app });

app.listen({ port: 4000 }, () =>
  console.log(`Server ready at http://localhost:4000${server.graphqlPath}`)
);

Other packages similar to apollo-server-express

express-graphql

The express-graphql package is a middleware for Express that allows you to create a GraphQL HTTP server. It is simpler and more lightweight compared to apollo-server-express, but it lacks some of the advanced features and integrations provided by Apollo Server, such as schema stitching, Apollo Federation, and built-in support for subscriptions.

graphql-yoga

graphql-yoga is a fully-featured GraphQL server that works with any GraphQL schema. It is built on top of Express and apollo-server, and it provides a simple and flexible API for building GraphQL servers. Compared to apollo-server-express, graphql-yoga offers a more opinionated setup with built-in support for features like subscriptions, file uploads, and GraphQL Playground.

mercurius

mercurius is a GraphQL adapter for Fastify, a fast and low-overhead web framework for Node.js. It provides a similar set of features to apollo-server-express, including schema stitching, subscriptions, and context management. However, it is designed to work specifically with Fastify, which offers better performance and scalability compared to Express.

README

This is the Express integration of Apollo Server. Apollo Server is a community-maintained open-source GraphQL server that works with many Node.js HTTP server frameworks. Read the docs. Read the CHANGELOG.

A full example of how to use apollo-server-express can be found in the docs.

Before Apollo Server 3, we officially supported using this package with connect as well. connect is an older framework that express evolved from. For now, we believe that this package is still compatible with connect and we even run tests against connect, but we may choose to break this compatibility at some point without a major version bump. If you rely on the ability to use Apollo Server with connect, you may wish to make your own integration.

Principles

GraphQL Server is built with the following principles in mind:

• By the community, for the community: GraphQL Server's development is driven by the needs of developers
• Simplicity: by keeping things simple, GraphQL Server is easier to use, easier to contribute to, and more secure
• Performance: GraphQL Server is well-tested and production-ready - no modifications needed

Anyone is welcome to contribute to GraphQL Server, just read CONTRIBUTING.md, take a look at the roadmap and make your first PR!