Using node-fetch with apollo-link-http

May 23, 2019

I'm building a Gatsby app that consumes data from a GraphQL service with the help of apollo-client and TypeScript. Because Gatsby creates static assets at build time, I needed a data-fetching tool that would work on the client-side and the server-side. apollo-client recommends using node-fetch for the task.

When I installed node-fetch and tried it out, I got this TypeScript error:

error TS7016: Could not find a declaration file for module 'node-fetch'. '/Users/mae.capozzi/Desktop/Codes/project/packages/client/node_modules/node-fetch/lib/index.js' implicitly has an 'any' type. Try `npm install @types/node-fetch` if it exists or add a new declaration (.d.ts) file containing `declare module 'node-fetch';` 8 import fetch from 'node-fetch';

Naturally, I installed @types/node-fetch. Rather than solving my problem, it led me to another one:

error TS2345: Argument of type '{ uri: string | undefined; credentials: string; fetch: typeof fetch; }' is not assignable to parameter of type 'Options'. Types of property 'fetch' are incompatible. Type 'typeof fetch' is not assignable to type '{ (input: RequestInfo, init?: RequestInit | undefined): Promise<Response>; (input: RequestInfo, init?: RequestInit | undefined): Promise<Response>; }'. Types of parameters 'url' and 'input' are incompatible. Type 'RequestInfo' is not assignable to type 'import("/Users/mae.capozzi/Desktop/Codes/project/node_modules/@types/node-fetch/index").RequestInfo'. Type 'Request' is not assignable to type 'RequestInfo'. Type 'Request' is missing the following properties from type 'Request': context, compress, counter, follow, and 6 more. 21 new HttpLink({ ~ 22 uri: process.env.GRAPHQL_SERVER_ENDPOINT, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ... 24 fetch, ~~~~~~~~~~~~ 25 }),

This error is basically saying that I have two different type declarations for fetch, and they are incompatible. In other words, apollo-client's type declaration for fetch doesn't match node-fetch's.

Thanks to a few hours of combing through Github issues, I found a solution hidden deep in the comments. In any d.ts file in your project, add:

// real node-fetch types clash with apollo-link-http, so manually define it as globalfetch here. declare module 'node-fetch' { const fetch: GlobalFetch['fetch']; export default fetch; }

I've opened an issue on the repo to add this information to the docs. You can find it here.

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