GraphQL Context & Services

GraphiQL

Having used GraphQL for quite some time, two of my favorite patterns are:

  • Context as a class

  • Abstracting complexity into **Service APIs **via context.services

*Note: *You can find the source code for this screenshot & demo at: https://github.com/ericclemmons/graphql-context-services/

Rationale

  • Using Context (instead of a plain {…} object) moves complexity from within your GraphQL middleware to a separate, testable layer.

  • Context can have a strict, testable API for your resolvers to use, instead of ad-hoc reliance on req.query or req.body.

This initialization pattern is compatible with Apollo’s Data Sources. Also, computed properties are readily testable without an E2E test.

  • API calls within resolvers are simplified, as their only responsibility is to shepherd arguments from the query to the service layer.

  • You can leverage Apollo’s dataSources, even with the standard express-graphql library!

RESTDataSource automatically caches based on HTTP response headers!

That’s it!

If you haven’t already, view & play with this example on CodeSandbox.

If you enjoyed this, give me a follow at @ericclemmons on Twitter!