graphql-api-koa

GraphQL API Koa middleware.

Setup

Install with peer dependencies using npm:

npm install graphql-api-koa graphql

API

Table of Contents

• errorHandler
  • Examples
• execute
  • Parameters
• Types
  • ExecuteOptions
    • Properties
  • MiddlewareOptionsOverride
    • Parameters
    • Examples

errorHandler

• See: GraphQL Draft RFC Specification October 2016 § 7.2.2.
• See: http-errors on npm.

Creates Koa middleware to handle errors. Use this middleware first to catch all errors for a correctly formated GraphQL response. For security, errors thrown outside resolvers without an expose property and true value are masked by a generic 500 error.

Examples

A basic GraphQL API.

import Koa from 'koa'
import bodyParser from 'koa-bodyparser'
import { errorHandler, execute } from 'graphql-api-koa'
import schema from './schema'

const app = new Koa()
  .use(errorHandler())
  .use(bodyParser())
  .use(execute({ schema }))

Returns Function Koa middleware.

execute

Creates Koa middleware to execute GraphQL. Use after the errorHandler and body parser middleware.

Parameters

• options ExecuteOptions Options.

Returns Function Koa middleware.

Types

The following types are for documentation only and are not exported.

ExecuteOptions

GraphQL execute Koa middleware options.

Type: Object

Properties

• schema module:graphql.GraphQLSchema GraphQL schema.
• rootValue any? Value passed to the first resolver.
• contextValue any? Execution context (usually an object) passed to resolvers.
• fieldResolver Function? Custom default field resolver.
• override MiddlewareOptionsOverride? Override any ExecuteOptions (except override) per request.

MiddlewareOptionsOverride

Per-request Koa middleware options override.

Type: Function

Parameters

• context module:koa.Context Koa context.

Examples

execute middleware options setting the schema once at startup and user context per-request.

import schema from './schema'

const executeOptions = {
  schema,
  override: ctx => ({
    contextValue: {
      user: ctx.user
    }
  })
}

Returns Object Options.