graphql-express-persisted-query

Express middleware to handle persisted (stored) GraphQL queries by ID

Purpose

As GraphQL needs mature and scale, saving queries to the server (or elsewhere) and referring to those by unique IDs can be useful. Stored queries decrease query size which could boost performance for clients on slow networks. Stored queries can be used to enforce security by allowing only whitelisted query execution in addition to providing a system of versioning.

Prior art

• https://github.com/apollographql/persistgraphql

Usage

This package exports an Express middleware (loadQuery) that accepts an object of keys of unique query IDs and values of stringified queries. When a query is made against your GraphQL server, this middleware:

• Inspects the query to see if there is a query in the request body and calls next() if a query is found.
• If a query is not found, we check for an id in the request body and attempt to look up the query by ID in the query map provided.
• If found, the query is added to req.body.query and next() is called.
• If a query is not found, the optional errorHandler is called or a 400 is returned.

This package also exports a function which can parse a directory for queries and generates a map that can be passed to loadQuery.

Example

//routes.js
import { loadQuery, createMapFromDir } from 'graphql-express-persisted-query';
import error400 from './app/errors/400';
import graphqlServer from './app/graphql';

const queryMap = createMapFromDir(path.resolve(__dirname, './queries'));
const queryErrorHandler = (req, res) => error400(req, res);

app.use(
    '/graphql',
    loadQuery(queryMap, queryErrorHandler),
    graphql
);