Codegen Autoloader

A plugin for the GraphQL Code Generator that scans a set of GraphQL schema files for directives that have been annotated with implementations and generates files that can be consumed by GraphQL implementations.

Usage

Install the package @amazeelabs/codegen-autoloader and add it to your codegen configuration:

schema: 'schema.graphql'
generates:
  generated/js/directives.mjs:
    plugins:
      - '@amazeelabs/codegen-autoloader'
    context:
      - gatsby
    mode: 'js'

Directives

To annotate a directive for auto-loading, add a block comment that includes a line starting with implementation:.

"""
implementation: @my-project/directives#my_echo
"""
directive @echo(msg: String!) repeatable on FIELD_DEFINITION

This will cause the autoloader to connect the @echo directive to the my_echo function exposed by the @my-project/directives package.

If the implementation contains ::, it will be considered a Drupal implementation. It is possible to execute methods of either static classes (\Drupal\my_modules\Directives::myEcho) or Symfony services (my_module.directives::myEcho). This has only an effect if the output mode is drupal.

Contexts

Contexts allow to annotate a directive with different implementations that will be applied, depending on the current execution context. The most prominent use case would be to define implementations of a given function for Gatsby and Drupal:

"""
implementation(gatsby): @my-project/directives#my_echo
implementation(drupal): \Drupal\my_project\Directives::my_echo
"""
directive @echo(msg: String!) repeatable on FIELD_DEFINITION

The codegen configuration the could simply generate multiple a file for each context:

schema: 'schema.graphql'
generates:
  generated/js/directives.mjs:
    plugins:
      - '@amazeelabs/codegen-autoloader'
    context:
      - gatsby
    mode: 'js'
  generated/drupal/directives.json:
    plugins:
      - '@amazeelabs/codegen-autoloader'
    context:
      - drupal
    mode: 'drupal'

Multiple contexts can be specified using comma-separated values:

"""
implementation(gatsby): @my-project/directives#responsiveImage
implementation(gatsby,cloudinary): @my-project/directives#responsiveImage
"""
directive @responsiveImage(url: String!) on FIELD_DEFINITION

An implementation will be picked when all of the specified contexts match.

schema: 'schema.graphql'
generates:
  generated/js/directives.mjs:
    plugins:
      - '@amazeelabs/codegen-autoloader'
    context:
      - gatsby
      - cloudinary
    mode: 'js'

Output modes

The mode configuration parameter allows to select the output mode. js creates a javascript file that exports a default object with the directives. drupal creates a JSON file with the directives that is compatible to amazeelabs/graphql_directives.