onVariants

Registering callbacks using onVariants in plugin

This recipe shows how to access and modify the variant objects in your project. Plugin demonstrates a possible usages of the onVariants() API in CustomPlugin.kt.

Module	Content
build-logic	Contains the Project plugin that is the core of the recipe.
app	An Android application that will be configured with additional variants.

The onVariants API differs from beforeVariants in that it gives access to the variants only after all the artifacts produced by AGP have been determined. This means the only values that can be modified are Property values, which are resolved during task execution. One of these properties is the application ID, which is used as an example in this recipe. These properties can then be wired up to providers from custom tasks, as this recipe demonstrates.

Details

Configuring variants

Variants are set with two predefined build types debug and release.

onVariants

The onVariants API also supports VariantSelectors.

Recipe has multiple examples of usage onVariants API in Kotlin:

Following snippet selects all variants with release build type and executes callback that updates the applicationId for those variants.

val releaseSelector = androidComponents.selector().withBuildType("release")

androidComponents.onVariants(releaseSelector) { variant ->
     variant.applicationId.set("newApplicationId")
}

More examples are in CustomPlugin.kt.

To Run

CustomPlugin registers an instance of a task CheckApplicationIdTask per variant, and this task verifies and outputs a modified application ID corresponding to the variant name.

To run the examples, you can just do

./gradlew checkDebugApplicationId

and you will see the output:

    Application ID for debug variant: debug.applicationId

Running with a different variant will produce the corresponding output.