persistgraphql

PersistGraphQL

persistgraphql is a simple build tool that enables query whitelisting and persisted queries for GraphQL projects that use statically analyze-able GraphQL queries.

It scans a code directory and extracts GraphQL query documents from .graphql files. It then assigns these queries ID values/hashes and produces a JSON file which maps from queries to hashes/IDs. This map can then be used by the client and server to perform query whitelisting, query lookups (i.e. client only sends the hash/id, the server just looks up the corresponding query), etc.

The npm package also provides a network interface for Apollo Client that manages the query lookups in persistgraphql/lib/browser. To see how to extract the queries on the server, see the code snippets below.

Installation

For only the CLI tool:

npm install -g persistgraphql

As a dependency (for Apollo Client network interface):

npm install --save persistgraphql

Build Tool Semantics

The build tool binary is called persistgraphql. Running it with no other arguments should give:

Usage: persistgraphql input_file [output file] [--add_typename]

It can be called on a file containing GraphQL query definitions with extension .graphql:

persistgraphql queries.graphql

It can also be called on a directory, which it will step through recursively:

persistgraphql src/

By default, the output will be placed in extracted_queries.json. An output file can be specified as the second argument:

persistgraphql index.ts output.json

Adding Typenames to Extracted Queries

It can also take the --add_typename flag which will apply a query transformation to the query documents, adding the __typename field at every level of the query. You must pass this option if your client code uses this query transformation.

persistgraphql src/ --add_typename

Extracting Queries from TypeScript

To extract GraphQL queries from TypeScript files, use --js --extension=ts.

persistgraphql src/index.js --js --extension=ts

Extracting Queries from JavaScript

It is also possible to extract GraphQL queries from JavaScript files using --extension=js --js.

persistgraphql src/index.js --js --extension=js

Apollo Client Network Interface

This package provides an implementation of an Apollo Client network interface that provides persisted query support. It serves as a drop-in replacement for the standard network interface and uses the query map given by persistgraphql in order to send only query hashes/ids to the serverather than the query document.

This package also provides a way for you to alter any generic NetworkInterface to use persisted queries from a provided query map with the addPersistedQueries(networkInterface: NetworkInterface, queryMap: OutputMap) function. This overrides the query member function of your network interface instance to replace your query with an id based on the query map provided.

See the implementation as well as some documentation for it within src/network_interface/ApolloNetworkInterface.ts.

Server-side

If you use the client network interface provided by this package, you can quickly roll your own middleware to get the GraphQL query instead of the query ID that the network interface sends. Here's an example with Express using the lodash invert method:

import queryMap from ‘../extracted_queries.json’;
import { invert } from 'lodash';
app.use(
  '/graphql',
  (req, resp, next) => {
    if (config.persistedQueries) {
      const invertedMap = invert(queryMap);
      req.body.query = invertedMap[req.body.id];
    }
    next();
  },
);

Here's an example with a Hapi server extension using the lodash invert method:

import queryMap from ‘../extracted_queries.json’;
import { invert } from 'lodash';
server.ext('onPreHandler', (req: Request, reply) => {
  if (config.persistedQueries && req.url.path.indexOf('/graphql') >= 0 && req.payload.id) {
    const invertedMap = invert(queryMap);
    req.payload.query = invertedMap[req.payload.id]
  }
  return reply.continue();
});