A Middleware for Persisted Queries with express-graphql

express-graphql-persisted-queries is an HTTP server middleware for persisted queries designed to work with express-graphql.

express-graphql-persisted-queries gives you a lot of flexibility by allowing you to specify a custom query ID key, a custom way to map a query ID to an actual query, and whether you want to allow only persisted queries for enhanced security.

express-graphql-persisted-queries also allows you to specify the persisted query ID both in the search params of a GET request and in the body of a POST request. This means that you can send HTTP GET requests for your GraphQL queries and laverage HTTP caching. This also means that you can preload queries with <link rel="preload">, starting to load data in parallel with code on the first page load.

Just like express-graphql, this middleware works with any HTTP web framework that supports connect styled middleware, including Connect, Express, and Restify.

Installation

Using yarn:

yarn add express-graphql-persisted-queries

Using npm:

npm install express-graphql-persisted-queries

Usage

express-graphql-persisted-queries exports its middleware as the persistedQueries named export. So, you should import it as follows:

// Using ES modules
import { persistedQueries } from 'express-graphql-persisted-queries';

// Using CommonJS
const { persistedQueries } = require('express-graphql-persisted-queries');

Here's an example of the most basic usage, which assumes that we are sending the query ID under the queryId key in the search params or request body, and that we store the mapping from query ID to query in a JSON file.

import queryMap from './queryMap.json';

app.use('/graphql', persistedQueries({ queryMap }), graphqlHTTP({ schema }));

Notice that the persistedQueries middleware should be used before graphqlHTTP.

Here's a more advanced example in which we specify a custom query ID key, use the database to map the query ID to a query, and allow only persisted queries in production:

app.use(
  '/graphql',
  persistedQueries({
    queryIdKey: 'id',
    queryMap: (queryId) => getQueryTextFromDatabase(queryId),
    strict: process.env.NODE_ENV === 'production',
  }),
  graphqlHTTP({ schema }),
);

API

persistedQueries(options: Options): Middleware

Parameters

• options: Options are the middleware options:

  • queryIdKey?: string (default: 'queryId') is the key in the search params or request body that specifies the ID of the persisted query.
  • queryMap: QueryMap is either an object mapping query IDs to query text or a function that receives the query ID as input and returns the query text, null, or a promise that resolves with query text or null. The QueryMap type is defined as follows:

    type QueryMap = Record<string, Maybe<string>> | QueryMapFn;
    type QueryMapFn = (queryId: string) => PromiseOrValue<Maybe<string>>;

  • strict?: boolean (default: false) specifies whether only persisted queries are allowed. When strict is true, any request that contains the query text or that does not contain a valid query ID is considered invalid and results in a 400 Bad Request error response.

Return value

• Middleware an HTTP server middleware.

Description

persistedQueries is used to create a middleware that adds support for persisted queries to your GraphQL HTTP server. This middleware should be specified before graphqlHTTP from express-graphql.

Example

app.use(
  '/graphql',
  persistedQueries({
    queryMap,
    strict: process.env.NODE_ENV === 'production',
  }),
  graphqlHTTP({ schema }),
);

Contributing

Your contributions are very welcome! To get started, read our contributing guidelines.

Also check out existing issues labeled as help wanted or good first issue.

License

MIT