Guide: GraphQL Modules

GraphQL Code Generator's @graphql-codegen/graphql-modules-preset plugin helps to generate resolvers type for each module of a GraphQL Modules GraphQL API.

Given the following GraphQL API structure using GraphQL Modules:

- src/
  - modules/
    - user/
      - resolvers.ts
      - typedefs/
        - user.graphql
    - product/
      - resolvers.ts
      - typedefs/
        - product.graphql

Just a few configuration steps are required to get the resolvers types generated:

Install

npm i -D @graphql-codegen/graphql-modules-preset @graphql-codegen/typescript-resolvers @graphql-codegen/typescript

Configure the plugin

Create or update your codegen.ts file as follows:

codegen.ts

import type { CodegenConfig } from '@graphql-codegen/cli'
 
const config: CodegenConfig = {
  schema: './src/modules/**/typedefs/*.graphql',
  generates: {
    './server/src/modules/': {
      preset: 'graphql-modules',
      presetConfig: {
        baseTypesPath: '../generated-types/graphql.ts',
        filename: 'generated-types/module-types.ts'
      },
      plugins: [
        {
          add: {
            content: '/* eslint-disable */'
          }
        },
        'typescript',
        'typescript-resolvers'
      ]
    }
  }
}
export default config

Run the codegen and update your code

Assuming that, as recommended, your package.json has the following script:

package.json

{
  "scripts": {
    "generate": "graphql-codegen"
  }
}

Running the following generates the graphql/generated.tsx file.

npm run generate

The User module resolvers would be:

src/modules/user/resolvers.ts

import { UsersModule } from './generated-types/module-types'
 
export const resolvers: UsersModule.Resolvers = {
  // Here, you can implement only the types and fields defined in your module!
}

A complete article, written by Arda Tanrikulu from The Guild, is available on our blog: Writing a GraphQL TypeScript project w/ GraphQL-Modules and GraphQL-Code-Generator.

For more advanced configuration (models or context typing), please refer to the plugin documentation.

API Testing Further Reading