mercurius-codegen

mercurius-codegen

Get full type-safety and autocompletion for Mercurius using TypeScript and GraphQL Code Generator seamlessly while you code.

pnpm add mercurius-codegen
# or
yarn add mercurius-codegen
# or
npm install mercurius-codegen

Usage

For convenience, this package also exports a fake gql tag that gives tooling support for "prettier formatting" and "IDE syntax highlighting". It's completely optional.

import Fastify from 'fastify'
import mercurius from 'mercurius'
import mercuriusCodegen, { gql } from 'mercurius-codegen'

const app = Fastify()

app.register(mercurius, {
  schema: gql`
    type Query {
      hello(greetings: String!): String!
    }
  `,
  resolvers: {
    Query: {
      hello(_root, { greetings }) {
        // greetings ~ string
        return 'Hello World'
      },
    },
  },
})

mercuriusCodegen(app, {
  targetPath: './src/generated/graphql.ts',
}).catch(console.error)

// Then it will automatically generate the file,
// and without doing anything special,
// the resolvers are going to be typed,
// or if your resolvers are in different files...

app.listen(8000)

import { IResolvers } from 'mercurius'

// Fully typed!
export const resolvers: IResolvers = {
  Query: {
    hello(_root, { greetings }) {
      // greetings ~ string
      return 'Hello World'
    },
  },
}

It also gives type-safety for Mercurius Loaders:

import { MercuriusLoaders } from 'mercurius'

// Fully typed!
export const loaders: MercuriusLoaders = {
  Dog: {
    async owner(queries, ctx) {
      // queries & ctx are typed accordingly
      return queries.map(({ obj, params }) => {
        // obj & params are typed accordingly
        return owners[obj.name]
      })
    },
  },
}

By default it disables itself if NODE_ENV is 'production'

It automatically uses prettier resolving the most nearby config for you.

Options

There are a couple extra options that can be specified:

interface CodegenMercuriusOptions {
  /**
   * Specify the target path of the code generation.
   *
   * Relative to the directory of the executed script if targetPath isn't absolute
   * @example './src/generated/graphql.ts'
   */
  targetPath: string
  /**
   * Disable the code generation manually, by default it's `process.env.NODE_ENV === 'production'`
   */
  disable?: boolean
  /**
   * Don't notify to the console
   */
  silent?: boolean
  /**
   * Specify GraphQL Code Generator configuration
   * @example
   * codegenConfig: {
   *    scalars: {
   *        DateTime: "Date",
   *    },
   *    defaultMapper: "DeepPartial<{T}>"
   * }
   * @default
   * codegenConfig: {
   *    defaultMapper: "DeepPartial<{T}>"
   * }
   */
  codegenConfig?: CodegenPluginsConfig
  /**
   * Add code in the beginning of the generated code
   */
  preImportCode?: string
}

mercuriusCodegen(app, {
  targetPath: './src/generated/graphql.ts',
  disable: false,
  silent: true,
  codegenConfig: {
    scalars: {
      DateTime: 'Date',
    },
    defaultMapper: 'DeepPartial<{T}>',
  },
  preImportCode: `
  // Here you can put any code and it will be added at very beginning of the file
  `,
}).catch(console.error)

License

MIT