OpenAPI Generator Gradle Plugin - Example of loading templates from classpath

This accompanies PR: OpenAPITools/openapi-generator#14909

Build the PR branch of the gradle plugin

It is expected that prior to running the below steps, you have first run:

$ git clone git@github.com:dimber-cais/openapi-generator.git openapi-generator-custom-templates
$ cd openapi-generator-custom-templates
$ git checkout feature/gradle-classpath-templates
$ cd modules/openapi-generator-gradle-plugin
$ /gradlew publishToMavenLocal

This will publish version 6.5.0-SNAPSHOT of the gradle plugin to your Maven local repository.

Use the local version of the gradle plugin

The root project is setup to utilize Gradle plugins within the local Maven repository. This is achieved via the following in the settings.gradle.kts file:

pluginManagement {
    repositories {
        mavenLocal()
    }
}

Publish a JAR containing customized templates

$ cd templates-module
$ gradle publishToMavenLocal

This will build the templates-module as a JAR and publish it to the local Maven repository. The JAR includes file custom-templates/README.mustache which will override the default template with this custom template.

Generate using customized templates from the classpath

The generator-module is setup to generate as:

openApiGenerate {
    generatorName.set("kotlin")
    library.set("jvm-retrofit2")
    packageName.set("com.example")
    inputSpec.set("${project.projectDir}/spec.yaml")
    generateApiDocumentation.set(false)
    generateApiTests.set(false)
    generateModelDocumentation.set(false)
    generateModelTests.set(false)
    outputDir.set("$buildDir/generated/sources/client")
    templateResourcePath.set("custom-templates")
}

The key setting here is templateResourcePath.set("custom-templates") which will cause the generate task to use the custom templates.

We also configure it to ensure that the custom templates JAR is available to the plugin's classpath:

buildscript {
    repositories {
        mavenLocal()
    }
    dependencies {
        classpath("com.example:templates-module:1.0")
    }
}

We can now execute the generate task:

$ cd generator-module
$ gradle openApiGenerate

We can see that the generated README.md has been changed to contain customized content:

$ cat build/generated/sources/client/README.md                                                                 
# CUSTOMIZED CLASSPATH TEMPLATE OUTPUT