GraphQL Kotlin Hooks Provider

This module provides SchemaGeneratorHooksProvider Service Provider Interface that is used by the GraphQL Kotlin Plugins to obtain an instance of SchemaGeneratorHooks that will be used to generate GraphQL schema.

interface SchemaGeneratorHooksProvider {

    /**
     * Create a new instance of a SchemaGeneratorHooks that will be used to generate GraphQL schema in SDL format.
     */
    fun hooks(): SchemaGeneratorHooks
}

Creating Custom Hooks Provider

SDL generator utilizes Java ServiceLoader to load available service providers from the classpath.

Create new SchemaGeneratorHooksProvider implementation

Service provider implementation has to implement SchemaGeneratorHooksProvider interface that provides a way to instantiate schema generator hooks that will be used to generate the GraphQL schema.

package com.example

class MyCustomSchemaGeneratorHooksProvider : SchemaGeneratorHooksProvider {
    override fun hooks(): SchemaGeneratorHooks = MyCustomHooks()
}

Create provider configuration file

Service loader provider configuration file should be created under JAR /META-INF/services directory (e.g. src/main/resources/META-INF/services in default project structure). Name of the provider configuration should be fully qualified service provider interface name, i.e. com.expediagroup.graphql.plugin.schema.hooks.SchemaGeneratorHooksProvider and contain single entry - a fully qualified name of the service provider implementation.

Using the example service provider implementation from the above, our project structure should look like

my-project
|- src
  |- main
    |- kotlin
      |- com
        |- example
          |- MyCustomSchemaGeneratorHooksProvider.kt
    |- resources
      |- META-INF
        |- services
          |- com.expediagroup.graphql.plugin.schema.hooks.SchemaGeneratorHooksProvider

Our service provider configuration file should have following content

com.example.MyCustomSchemaGeneratorHooksProvider

Limitations

We don't support Java 9 module mechanism for declaring ServiceLoader implementations. As a workaround, you have to define your service providers in the provider configuration file under META-INF/services.