Using Relay with AWS AppSync

Before addressing the specific requirements of Relay, it’s worth spending a moment on some core GraphQL and AppSync concepts. Here are a few that will be discussed throughout the post:

The unique ID requirement is very easy to achieve with AppSync, and corresponds very well to a persistence layer consisting of a single DynamoDB table, as is used in the sample app (just make sure all the types in the GraphQL API have a unique ID called “id” — this is a firm requirement of Relay).

The other requirements for connections and mutations deserve a little more attention.

This can be queried like:

A simple response mapping template for a DynamoDB query for Todos could look something like this:

However, that would just give us a simple “flat list” of results, which does not match the format required by Relay. Here is a mapping template that gives us what we need:

Relay also has some specific requirements of the inputs and outputs of mutations (updates/deletes/etc). Take a look at this subset of our schema handling Todo updates in compliance with the spec (creates and deletes are handled similarly):

Once the API backend is set up, all that’s left is to get the frontend to talk to it. Fortunately, the AWS Amplify client library makes this really easy. In fact, the entire integration between AppSync and Relay on the frontend is achieved with this one short source file:

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