by graphql

Create a GraphQL HTTP server with Express.

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GraphQL HTTP Server Middleware

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Create a GraphQL HTTP server with any HTTP web framework that supports connect styled middleware, including Connect itself, Express and Restify.


npm install --save express-graphql


This module includes a TypeScript declaration file to enable auto complete in compatible editors and type information for TypeScript projects.

Simple Setup

Just mount

as a route handler:
const express = require('express');
const { graphqlHTTP } = require('express-graphql');

const app = express();

app.use( '/graphql', graphqlHTTP({ schema: MyGraphQLSchema, graphiql: true, }), );


Setup with Restify


(or both) rather than
to configure your route handler. If you want to show GraphiQL in the browser, set
graphiql: true
on your
const restify = require('restify');
const { graphqlHTTP } = require('express-graphql');

const app = restify.createServer(); '/graphql', graphqlHTTP({ schema: MyGraphQLSchema, graphiql: false, }), );

app.get( '/graphql', graphqlHTTP({ schema: MyGraphQLSchema, graphiql: true, }), );




function accepts the following options:
  • schema
    : A

    instance from
    . A
    must be provided.
  • graphiql
    : If

    , presents GraphiQL when the GraphQL endpoint is loaded in a browser. We recommend that you set
    when your app is in development, because it's quite useful. You may or may not want it in production. Alternatively, instead of
    you can pass in an options object:
    • defaultQuery
      : An optional GraphQL string to use when no query is provided and no stored query exists from a previous session. If undefined is provided, GraphiQL will use its own default query.
    • headerEditorEnabled
      : An optional boolean which enables the header editor when true. Defaults to false.
  • rootValue
    : A value to pass as the

    to the
    function from
  • context
    : A value to pass as the

    to the
    function from
    . If
    is not provided, the
    object is passed as the context.
  • pretty
    : If

    , any JSON response will be pretty-printed.
  • extensions
    : An optional function for adding additional metadata to the GraphQL response as a key-value object. The result will be added to the

    field in the resulting JSON. This is often a useful place to add development time metadata such as the runtime of a query or the amount of resources consumed. This may be an async function. The function is given one object as an argument:
    { document, variables, operationName, result, context }
  • validationRules
    : Optional additional validation rules queries must satisfy in addition to those defined by the GraphQL spec.

  • customValidateFn
    : An optional function which will be used to validate instead of default

  • customExecuteFn
    : An optional function which will be used to execute instead of default

  • customFormatErrorFn
    : An optional function which will be used to format any errors produced by fulfilling a GraphQL operation. If no function is provided, GraphQL's default spec-compliant
    function will be used.

  • customParseFn
    : An optional function which will be used to create a document instead of the default

  • formatError
    : is deprecated and replaced by

    . It will be removed in version 1.0.0.

In addition to an object defining each option, options can also be provided as a function (or async function) which returns this options object. This function is provided the arguments

(request, response, graphQLParams)
and is called after the request has been parsed.


is provided as the object
{ query, variables, operationName, raw }
  graphqlHTTP(async (request, response, graphQLParams) => ({
    schema: MyGraphQLSchema,
    rootValue: await someFunctionToGetRootValue(request),
    graphiql: true,

HTTP Usage

Once installed at a path,

will accept requests with the parameters:
  • query
    : A string GraphQL document to be executed.

  • variables
    : The runtime values to use for any GraphQL query variables as a JSON object.

  • operationName
    : If the provided

    contains multiple named operations, this specifies which operation should be executed. If not provided, a 400 error will be returned if the
    contains multiple named operations.
  • raw
    : If the

    option is enabled and the
    parameter is provided raw JSON will always be returned instead of GraphiQL even when loaded from a browser.

GraphQL will first look for each parameter in the query string of a URL:


If not found in the query-string, it will look in the POST request body.

If a previous middleware has already parsed the POST body, the

value will be used. Use
or a similar middleware to add support for
content, which may be useful for GraphQL mutations involving uploading files. See an example using multer.

If the POST body has not yet been parsed, express-graphql will interpret it depending on the provided Content-Type header.

  • application/json
    : the POST body will be parsed as a JSON object of parameters.

  • application/x-www-form-urlencoded
    : this POST body will be parsed as a url-encoded string of key-value pairs.

  • application/graphql
    : The POST body will be parsed as GraphQL query string, which provides the


Combining with Other Express Middleware

By default, the express request is passed as the GraphQL

. Since most express middleware operates by adding extra data to the request object, this means you can use most express middleware just by inserting it before
is mounted. This covers scenarios such as authenticating the user, handling file uploads, or mounting GraphQL on a dynamic endpoint.

This example uses

to provide GraphQL with the currently logged-in session.

const session = require('express-session');
const { graphqlHTTP } = require('express-graphql');

const app = express();

app.use(session({ secret: 'keyboard cat', cookie: { maxAge: 60000 } }));

app.use( '/graphql', graphqlHTTP({ schema: MySessionAwareGraphQLSchema, graphiql: true, }), );

Then in your type definitions, you can access the request via the third "context" argument in your

new GraphQLObjectType({
  name: 'MyType',
  fields: {
    myField: {
      type: GraphQLString,
      resolve(parentValue, args, request) {
        // use `request.session` here

Providing Extensions

The GraphQL response allows for adding additional information in a response to a GraphQL query via a field in the response called

. This is added by providing an
function when using
. The function must return a JSON-serializable Object.

When called, this is provided an argument which you can use to get information about the GraphQL request:

{ document, variables, operationName, result, context }

This example illustrates adding the amount of time consumed by running the provided query, which could perhaps be used by your development tools.

const { graphqlHTTP } = require('express-graphql');

const app = express();

app.use(session({ secret: 'keyboard cat', cookie: { maxAge: 60000 } }));

const extensions = ({ document, variables, operationName, result, context, }) => { return { runTime: - context.startTime, }; };

app.use( '/graphql', graphqlHTTP((request) => { return { schema: MyGraphQLSchema, context: { startTime: }, graphiql: true, extensions, }; }), );

When querying this endpoint, it would include this information in the result, for example:

  "data": { ... }
  "extensions": {
    "runTime": 135

Additional Validation Rules

GraphQL's validation phase checks the query to ensure that it can be successfully executed against the schema. The

option allows for additional rules to be run during this phase. Rules are applied to each node in an AST representing the query using the Visitor pattern.

A validation rule is a function which returns a visitor for one or more node Types. Below is an example of a validation preventing the specific field name

from being queried. For more examples see the
in the graphql-js package.
import { GraphQLError } from 'graphql';

export function DisallowMetadataQueries(context) { return { Field(node) { const fieldName =;

  if (fieldName === 'metadata') {
      new GraphQLError(
        `Validation: Requesting the field ${fieldName} is not allowed`,

}; }

Disabling introspection

Disabling introspection does not reflect best practices and does not necessarily make your application any more secure. Nevertheless, disabling introspection is possible by utilizing the

provided by the graphql-js package.
import { specifiedRules, NoSchemaIntrospectionCustomRule } from 'graphql';

app.use( '/graphql', graphqlHTTP((request) => { return { schema: MyGraphQLSchema, validationRules: [...specifiedRules, NoSchemaIntrospectionCustomRule], }; }), );

Other Exports

getGraphQLParams(request: Request): Promise

Given an HTTP Request, this returns a Promise for the parameters relevant to running a GraphQL request. This function is used internally to handle the incoming request, you may use it directly for building other similar services.

const { getGraphQLParams } = require('express-graphql');

getGraphQLParams(request).then((params) => { // do something... });

Debugging Tips

During development, it's useful to get more information from errors, such as stack traces. Providing a function to

enables this:
customFormatErrorFn: (error) => ({
  message: error.message,
  locations: error.locations,
  stack: error.stack ? error.stack.split('\n') : [],
  path: error.path,

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