GraphQL.js

A JavaScript implementation of GraphQL, a query language for APIs created by Facebook.

The purpose of this fork is to increase the velocity with which we at Apollo are able to improve the graphql implementation, while also gradually converting it from Flow to TypeScript.

See more complete documentation at https://graphql.org/ and https://graphql.org/graphql-js/.

Looking for help? Find resources from the community.

Getting Started

An overview of GraphQL in general is available in the README for the Specification for GraphQL. That overview describes a simple set of GraphQL examples that exist as tests in this repository. A good way to get started with this repository is to walk through that README and the corresponding tests in parallel.

Using GraphQL.js

Install GraphQL.js from npm

npm install --save @apollo/graphql

GraphQL.js provides two important capabilities: building a type schema, and serving queries against that type schema.

First, build a GraphQL type schema which maps to your code base.

import {
  graphql,
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLString,
} from '@apollo/graphql';

var schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'RootQueryType',
    fields: {
      hello: {
        type: GraphQLString,
        resolve() {
          return 'world';
        },
      },
    },
  }),
});

This defines a simple schema with one type and one field, that resolves to a fixed value. The resolve function can return a value, a promise, or an array of promises. A more complex example is included in the top level tests directory.

Then, serve the result of a query against that type schema.

var query = '{ hello }';

graphql(schema, query).then(result => {
  // Prints
  // {
  //   data: { hello: "world" }
  // }
  console.log(result);
});

This runs a query fetching the one field defined. The graphql function will first ensure the query is syntactically and semantically valid before executing it, reporting errors otherwise.

var query = '{ boyhowdy }';

graphql(schema, query).then(result => {
  // Prints
  // {
  //   errors: [
  //     { message: 'Cannot query field boyhowdy on RootQueryType',
  //       locations: [ { line: 1, column: 3 } ] }
  //   ]
  // }
  console.log(result);
});

Using in a Browser

GraphQL.js is a general purpose library and can be used both in a Node server and in the browser. As an example, the GraphiQL tool is built with GraphQL.js!

Building a project using GraphQL.js with webpack or rollup should just work and only include the portions of the library you use. This works because GraphQL.js is distributed with both CommonJS (require()) and ESModule (import) files. Ensure that any custom build configurations look for .mjs files!

Contributing

Read the Apollo Contributor Guidelines.

TypeScript

Part of this fork's purpose is to begin a gradual migration of graphql-js from Flow to TypeScript. Some parts have already been converted, and some remain to be converted. The steps for converting a file from Flow to TypeScript are as follows:

1. Rename the file, and convert syntax to TypeScript: Foo.js becomes Foo.ts, and any Flow specific syntax should be transalted.
2. Create a Foo.js.flow type declaration file for the file's exports (Foo.d.ts, if present, can be helpful for guiding this process). Make sure you prefix the file with // @flow, or else strange things will happen!
3. Delete the Foo.d.ts file, if it exists.
4. Run npm run check, and ensure both flow and tsc typecheck the project without issue.

Check out 45da517 for an example of this process.

Changelog

Changes are tracked as GitHub releases.

License

GraphQL.js is MIT-licensed.

Credits

The .d.ts files in this project are, in part, from @types/graphql, written by:

• TonyYang https://github.com/TonyPythoneer
• Caleb Meredith https://github.com/calebmer
• Dominic Watson https://github.com/intellix
• Firede https://github.com/firede
• Kepennar https://github.com/kepennar
• Mikhail Novikov https://github.com/freiksenet
• Ivan Goncharov https://github.com/IvanGoncharov
• Hagai Cohen https://github.com/DxCx
• Ricardo Portugal https://github.com/rportugal
• Tim Griesser https://github.com/tgriesser
• Dylan Stewart https://github.com/dyst5422
• Alessio Dionisi https://github.com/adnsio
• Divyendu Singh https://github.com/divyenduz
• Brad Zacher https://github.com/bradzacher
• Curtis Layne https://github.com/clayne11
• Jonathan Cardoso https://github.com/JCMais
• Pavel Lang https://github.com/langpavel
• Mark Caudill https://github.com/mc0
• Martijn Walraven https://github.com/martijnwalraven
• Jed Mao https://github.com/jedmao

And licensed under the MIT License.

Thanks to all the above contributors!