use_express.md

graphql-http / use/express

Module: use/express

Table of contents

Interfaces

• RequestContext

Type Aliases

• HandlerOptions

Functions

• createHandler
• parseRequestParams

Server/express

HandlerOptions

Ƭ HandlerOptions<Context>: HandlerOptions<Request, RequestContext, Context>

Handler options when using the express adapter.

Type parameters

Name	Type
Context	extends OperationContext = undefined

---

createHandler

▸ createHandler<Context>(options): Handler

Create a GraphQL over HTTP spec compliant request handler for the express framework.

import express from 'express'; // yarn add express
import { createHandler } from 'graphql-http/lib/use/express';
import { schema } from './my-graphql-schema';

const app = express();
app.all('/graphql', createHandler({ schema }));

app.listen({ port: 4000 });
console.log('Listening to port 4000');

Type parameters

Name	Type
Context	extends OperationContext = undefined

Parameters

Name	Type
options	HandlerOptions<Context>

Returns

Handler

---

parseRequestParams

▸ parseRequestParams(req, res): Promise<RequestParams | null>

The GraphQL over HTTP spec compliant request parser for an incoming GraphQL request.

If the HTTP request is not a well-formatted GraphQL over HTTP request, the function will respond on the Response argument and return null.

If the HTTP request is a well-formatted GraphQL over HTTP request, but is invalid or malformed, the function will throw an error and it is up to the user to handle and respond as they see fit.

import express from 'express'; // yarn add express
import { parseRequestParams } from 'graphql-http/lib/use/express';

const app = express();
app.all('/graphql', async (req, res) => {
  try {
    const maybeParams = await parseRequestParams(req, res);
    if (!maybeParams) {
      // not a well-formatted GraphQL over HTTP request,
      // parser responded and there's nothing else to do
      return;
    }

    // well-formatted GraphQL over HTTP request,
    // with valid parameters
    res.writeHead(200).end(JSON.stringify(maybeParams, null, '  '));
  } catch (err) {
    // well-formatted GraphQL over HTTP request,
    // but with invalid parameters
    res.writeHead(400).end(err.message);
  }
});

app.listen({ port: 4000 });
console.log('Listening to port 4000');

Parameters

Name	Type
req	Request<ParamsDictionary, any, any, ParsedQs, Record<string, any>>
res	Response<any, Record<string, any>>

Returns

Promise<RequestParams | null>