express-graphql

What is express-graphql?

The express-graphql package is a middleware for integrating GraphQL with an Express server. It allows you to create a GraphQL HTTP server with Express, enabling you to define a schema, resolve functions, and handle GraphQL queries and mutations.

What are express-graphql's main functionalities?

Setting up a basic GraphQL server

This code sets up a basic GraphQL server using express-graphql. It defines a simple schema with a single query 'hello' and a root resolver that returns 'Hello world!'. The server listens on port 4000 and provides a GraphiQL interface for testing queries.

const express = require('express');
const { graphqlHTTP } = require('express-graphql');
const { buildSchema } = require('graphql');

const schema = buildSchema(`
  type Query {
    hello: String
  }
`);

const root = { hello: () => 'Hello world!' };

const app = express();
app.use('/graphql', graphqlHTTP({
  schema: schema,
  rootValue: root,
  graphiql: true,
}));

app.listen(4000, () => console.log('Now browse to localhost:4000/graphql'));

Enabling GraphiQL interface

This code demonstrates how to enable the GraphiQL interface, an in-browser IDE for exploring GraphQL. By setting the 'graphiql' option to true, you can navigate to '/graphql' in your browser and interact with your GraphQL API.

const express = require('express');
const { graphqlHTTP } = require('express-graphql');
const { buildSchema } = require('graphql');

const schema = buildSchema(`
  type Query {
    hello: String
  }
`);

const root = { hello: () => 'Hello world!' };

const app = express();
app.use('/graphql', graphqlHTTP({
  schema: schema,
  rootValue: root,
  graphiql: true,
}));

app.listen(4000, () => console.log('Now browse to localhost:4000/graphql'));

Handling mutations

This code shows how to handle mutations in a GraphQL server. It defines a schema with a 'setMessage' mutation and a 'getMessage' query. The 'setMessage' mutation updates a message variable, and the 'getMessage' query retrieves the current message.

const express = require('express');
const { graphqlHTTP } = require('express-graphql');
const { buildSchema } = require('graphql');

const schema = buildSchema(`
  type Mutation {
    setMessage(message: String): String
  }
  type Query {
    getMessage: String
  }
`);

let message = 'Hello world!';

const root = {
  setMessage: ({ message: newMessage }) => {
    message = newMessage;
    return message;
  },
  getMessage: () => message,
};

const app = express();
app.use('/graphql', graphqlHTTP({
  schema: schema,
  rootValue: root,
  graphiql: true,
}));

app.listen(4000, () => console.log('Now browse to localhost:4000/graphql'));

Other packages similar to express-graphql

apollo-server-express

Apollo Server is a community-maintained open-source GraphQL server that works with various Node.js HTTP server frameworks, including Express. It provides a more feature-rich and flexible solution compared to express-graphql, with built-in support for schema stitching, subscriptions, and more.

graphql-yoga

GraphQL Yoga is a fully-featured GraphQL server with focus on easy setup, performance, and great developer experience. It is built on top of Apollo Server and Express, offering additional features like out-of-the-box support for GraphQL subscriptions and file uploads.

README

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