relay-compiler-language-typescript

A language plugin for Relay that adds TypeScript support, including emitting type definitions.

Installation

Add the package to your dev dependencies:

yarn add graphql relay-compiler --dev
yarn add typescript relay-compiler-language-typescript --dev

Note: Starting with version 14.0.0 relay-compiler-language-typescript requires a minimum TypeScript version of 4.2.3 being installed in your project.

Configuration

relay-compiler

Then configure your relay-compiler script to use it, like so:

{
  "scripts": {
    "relay":
      "relay-compiler --src ./src --schema data/schema.graphql --language typescript --artifactDirectory ./src/__generated__"
  }
}

This is going to store all artifacts in a single directory, which you also need to instruct babel-plugin-relay to use in your .babelrc:

{
  "plugins": [["relay", { "artifactDirectory": "./src/__generated__" }]]
}

TypeScript

Also be sure to configure the TypeScript compiler to transpile to ES2015 modules (or higher) and leave transpilation to CommonJS modules (if required) up to Babel with the following tsconfig.json settings:

{
  "compilerOptions": {
    "module": "ES2015", // ES2015 or higher
    "target": "ES2020"  // best use the highest target setting compatible with your Babel setup
  }
}

The reason for this is that tsc would otherwise generate code where the imported graphql function is being namespaced (react_relay_1 in this example):

react_relay_1.createFragmentContainer(
  MyComponent,
  react_relay_1.graphql`
  ...
`
);

… which makes it impossible for babel-plugin-relay to find the locations where the graphql function is being used.

The generated code uses ES2015 module syntax if module is set to ES2015 or higher in your tsconfig.json. Note that the eagerESModules option from relay-compiler has no effect on the generated code if module is ES2015 or higher.

Custom Headers

If you need to add a custom header to generated files, perhaps for a custom linter or to get boilerplate license code in, that can be passed in also in compilerOptions as banner:

{
  "compilerOptions": {
    "banner": "/* © 2021 Example.org - @generated code */"
  }
}

Problems

React Hot Loader

React Hot Loader is known to not always work well with generated code such as our typing artifacts, which will lead to loading modules with TypeScript types into the browser and break. As a maintainer of RHL pointed out in a similar issue:

The problem - hot reloading is not "complete"

So until RHL will be made “complete” this project can’t gurantee to always work well with it, nor is it our control to do anything about that.

Also see

• You can find a copy of the Relay example TODO app inside this repository or you can take a look at the Artsy React Native app.
• There are Relay tslint rules available here.

License

This package is available under the MIT license. See the included LICENSE file for details.