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Running Express + GraphQL

The simplest way to run a GraphQL API server is to use Express, a popular web application framework for Node.js. You will need to install two additional dependencies:

npm install express graphql-http graphql --save

Let’s modify our “hello world” example so that it’s an API server rather than a script that runs a single query. We can use the ‘express’ module to run a webserver, and instead of executing a query directly with the graphql function, we can use the graphql-http library to mount a GraphQL API server on the “/graphql” HTTP endpoint:

const { buildSchema } = require('graphql');
const { createHandler } = require('graphql-http/lib/use/express');
const express = require('express');
 
// Construct a schema, using GraphQL schema language
const schema = buildSchema(`type Query { hello: String } `);
 
// The rootValue provides a resolver function for each API endpoint
const rootValue = {
  hello() {
    return 'Hello world!';
  },
};
 
const app = express();
 
// Create and use the GraphQL handler.
app.all(
  '/graphql',
  createHandler({
    schema: schema,
    rootValue: root,
  }),
);
 
// Start the server at port
app.listen(4000);
console.log('Running a GraphQL API server at http://localhost:4000/graphql');

You can run this GraphQL server with:

node server.js

Using GraphiQL

GraphiQL is GraphQL’s IDE; a great way of querying and exploring your GraphQL API. One easy way to add it to your server is via the MIT-licensed ruru package which bundles a prebuilt GraphiQL with some popular enhancements. To do so, install the ruru module with npm install --save ruru and then add the following to your server.js file, then restart the node server.js command:

const { ruruHTML } = require('ruru/server');
 
// Serve the GraphiQL IDE.
app.get('/', (_req, res) => {
  res.type('html');
  res.end(ruruHTML({ endpoint: '/graphql' }));
});

If you navigate to http://localhost:4000, you should see an interface that lets you enter queries; now you can use the GraphiQL IDE tool to issue GraphQL queries directly in the browser.

At this point you have learned how to run a GraphQL server. The next step is to learn how to issue GraphQL queries from client code.

Getting StartedGraphQL Clients