Apollo HTTP Data Source

Optimized JSON HTTP Data Source for Apollo Server

• Uses Undici under the hood. It's around 60% faster than apollo-datasource-rest
• Request Deduplication (LRU)
• Support AbortController to manually cancel all running requests

Documentation

View the Apollo Server documentation for data sources for more details.

Usage

To get started, install the @llc1123/apollo-datasource-http package:

npm install @llc1123/apollo-datasource-http

To define a data source, extend the HTTPDataSource class and implement the data fetching methods that your resolvers require. Data sources can then be provided via the dataSources property to the ApolloServer constructor, as demonstrated in the section below.

// instantiate a pool outside of your hotpath
const baseURL = 'https://movies-api.example.com'
const pool = new Pool(baseURL)

const server = new ApolloServer({
  typeDefs,
  resolvers,
  dataSources: () => {
    return {
      moviesAPI: new MoviesAPI(baseURL, pool),
    }
  },
})

Your implementation of these methods can call on convenience methods built into the HTTPDataSource class to perform HTTP requests, while making it easy to pass different options and handle errors.

import { Pool } from 'undici'
import { HTTPDataSource } from '@llc1123/apollo-datasource-http'

const datasource = new (class MoviesAPI extends HTTPDataSource {
  constructor(baseURL: string, pool: Pool) {
    // global client options
    super(baseURL, {
      pool,
      clientOptions: {
        bodyTimeout: 5000,
        headersTimeout: 2000,
      },
      requestOptions: {
        headers: {
          'X-Client': 'client',
        },
      },
    })
  }

  onCacheKeyCalculation(request: Request): string {
    // return different key based on request options
  }

  async onRequest(request: Request): Promise<void> {
    // manipulate request before it is send
    // for example assign a AbortController signal to all requests and abort

    request.signal = this.context.abortController.signal

    setTimeout(() => {
      this.context.abortController.abort()
    }, 3000).unref()
  }

  onResponse<TResult = unknown>(request: Request, response: Response<TResult>): Response<TResult> {
    // manipulate response or handle unsuccessful response in a different way
    return super.onResponse(request, response)
  }

  onError(error: Error, request: Request): void {
    // in case of a request error
    if (error instanceof RequestError) {
      console.log(error.request, error.response)
    }
  }

  async createMovie() {
    return this.post('/movies', {
      body: {
        name: 'Dude Where\'s My Car',
      }
    })
  }

  async getMovie(id) {
    return this.get(`/movies/${id}`, {
      query: {
        a: 1,
      },
      context: {
        tracingName: 'getMovie',
      },
      headers: {
        'X-Foo': 'bar',
      },
    })
  }
})()

Hooks

• onCacheKeyCalculation - Returns the cache key for request memoization.
• onRequest - Is executed before a request is made. This can be used to intercept requests (setting header, timeouts ...).
• onResponse - Is executed when a response has been received. This can be used to alter the response before it is passed to caller or to log errors.
• onError - Is executed for any request error.

Error handling

The http client throws for unsuccessful responses (statusCode >= 400). In case of an request error onError is executed. By default the error is rethrown as a ApolloError to avoid exposing sensible information.

Node.js support

We test this software against latest major releases of the Node.js LTS policy. Current is included to catch regression earlier.