Persisted queries

"Persisted queries" is a technique to improves network performance for GraphQL by sending an ID or hash instead of a long GraphQL query string.

While Benzene does not have persisted query built-in, it allows flexible persisted query implementation.

This can be done by modifying the request before passing it to handler functions.

Automatic Persisted Queries with @benzene/extra

Example

@benzene/extra includes a module to process persisted queries by taking in a GraphQLParams object.

If the persisted query is found, it will return a new GraphQLParams object with the found query. Otherwise, it will return an execution result.

import { Benzene, makeHandler } from "@benzene/http";
import { makeAPQHandler } from "@benzene/extra";
 
const apq = makeAPQHandler();
 
const GQL = new Benzene({ schema });
 
const graphqlHTTP = makeHandler(GQL, {
  onParams(params) {
    return apq(params);
  },
});
 
async function onRequest(req, res) {
  const result = await graphqlHTTP({
    body: req.body,
    query: req.query,
    method: req.method,
    headers: req.headers,
  });
  res
    .writeHead(result.status, result.headers)
    .end(JSON.stringify(result.payload));
}

Custom implementation

This recipe is not just limited to the popular APQ and @benzene/extra is not the only option.

For example, a middleware like relay-compiler-plus can be used to implement Relay-compatible persisted query.

import Express from "express";
import expressGraphql from "express-graphql";
import { matchQueryMiddleware } from "relay-compiler-plus";
import queryMapJson from "./path/to/persisted-queries.json";
 
const app = Express();
 
app.use("/graphql", matchQueryMiddleware(queryMapJson), (req, res) => {
  const result = await graphqlHTTP({
    body: req.body,
    query: req.query,
    method: req.method,
    headers: req.headers,
  });
  res.set(result.headers).status(result.status).send(result.payload);
});

You can also implement it yourself with something like the below:

const cache = lru();
 
async function onRequest(req, res) {
  const body = {
    variables: { foo: "bar" },
    documentId: "3be4abb81fa595e25eb725b2c6a87508",
  };
 
  if (body.documentId) {
    const query = cache.get(body.extensions.persisted);
    if (query) {
      body.query = query; // Add query to body using persisted query
    } else {
      // rejects arbitrary queries for securities
      return res.status(400).send({
        errors: [new GraphQLError("Only allow recognized persisted queries")],
      });
    }
  }
 
  const result = await graphqlHTTP({
    body: req.body,
  });
}