@prezly/contentful-typescript-codegen

contentful-typescript-codegen

Generate typings from your Contentful environment.

• Content Types become interfaces.
• Locales (and your default locale) become string types.
• Assets and Rich Text link to Contentful's types.

At Prezly, we use this in our marketing site to increase developer confidence and productivity, ensure that breaking changes to our Content Types don't cause an outage, and because it's neat.

Usage

npm i -D @prezly/contentful-typescript-codegen

Then, add the following to your package.json:

{
  // ...
  "scripts": {
    "contentful-typescript-codegen": "contentful-typescript-codegen --output @types/generated/contentful.d.ts"
  }
}

Feel free to change the output path to whatever you like.

Next, the codegen will expect you to have created a file called getContentfulEnvironment.js in the root of your project directory, and it should export a promise that resolves with your Contentful environment.

The reason for this is that you can do whatever you like to set up your Contentful Management Client. Here's an example:

const contentfulManagement = require("contentful-management")

module.exports = function() {
  const contentfulClient = contentfulManagement.createClient({
    accessToken: process.env.CONTENTFUL_MANAGEMENT_API_ACCESS_TOKEN,
  })

  return contentfulClient
    .getSpace(process.env.CONTENTFUL_SPACE_ID)
    .then(space => space.getEnvironment(process.env.CONTENTFUL_ENVIRONMENT))
}

Optionally, you can add a file called getContentfulFieldOverrides.js in the root of your project, which should export two functions:

1. getImports which should return an array of import declarations (as strings) required for your overriden types.
2. getOverridenContentTypes that returns an object of OverridenContentTypes type (see example), which will indicate which fields for which content types should be overriden with the type name you provided.

Example:

function getImports() {
  return [
    "import { SomeLibraryType } from '@some-library';"
  ]
}

function getOverridenContentTypes() {
  return {
    'myContentTypeId': {
      'overridenField': 'SomeLibraryType'
    }
  }
}

module.exports = {
  getImports,
  getOverridenContentTypes,
}

Command line options

Usage
  $ contentful-typescript-codegen --output <file> <options>

Options
  --output,      -o  Where to write to
  --poll,        -p  Continuously refresh types
  --interval N,  -i  The interval in seconds at which to poll (defaults to 15)

Example output

Here's an idea of what the output will look like for a Content Type:

interface BlogPostFields {
  /** Title */
  title: string

  /** Body */
  body: Document

  /** Author link */
  author: Author

  /** Image */
  image: Asset

  /** Published? */
  published: boolean | null

  /** Tags */
  tags: string[]

  /** Blog CTA variant */
  ctaVariant: "new-cta" | "old-cta"
}

/**
 * A blog post.
 */
export interface BlogPost extends Entry<BlogPostFields> {}

You can see that a few things are handled for you:

• Documentation comments are automatically generated from Contentful descriptions.
• Links, like author, are resolved to other TypeScript interfaces.
• Assets are handled properly.
• Validations on symbols and text fields are expanded to unions.
• Non-required attributes automatically have | null appended to their type.
• The output is formatted using your Prettier config.