How to configure the processResources task in a Gradle Kotlin build

Question

I have the following in a groovy-based build script. How do I do the same in a kotlin-based script?

processResources {

    filesMatching('application.properties'){
        expand(project.properties)
    }

}

Playboy

Answer 1

I think task should look like:

Edit: According this comment in gradle/kotlin-dsl repository. Task configuration should work this way:

import org.gradle.language.jvm.tasks.ProcessResources

apply {
    plugin("java")
}

(tasks.getByName("processResources") as ProcessResources).apply {
    filesMatching("application.properties") {
        expand(project.properties)
    }
}

Which is pretty ugly. So i suggest following utility function for this purpose, until one upstream done:

configure<ProcessResources>("processResources") {
    filesMatching("application.properties") {
        expand(project.properties)
    }
}

inline fun <reified C> Project.configure(name: String, configuration: C.() -> Unit) {
    (this.tasks.getByName(name) as C).configuration()
}

Telmatelo

That looks like it should work but I get an error. I think it could be a bug. Logged it here: discuss.gradle.org/t/… – Playboy

See the answer by @Heartthrob for a cleaner answer https://mcmap.net/q/757960/-how-to-configure-the-processresources-task-in-a-gradle-kotlin-build – Starwort

It was helpful. I'd like someone to make an groovy to kotlin-dsl converter! – Costive

Answer 2

Why not to just use "withType" ? I just mean (IMHO)

tasks {
  withType<ProcessResources> {
.. 
}

looks much better than

tasks {
  "processResources"(ProcessResources::class) {
.. 
}

So,

tasks.withType<ProcessResources> {
    //from("${project.projectDir}src/main/resources")
    //into("${project.buildDir}/whatever/")
    filesMatching("*.cfg") {
        expand(project.properties)
    }
}

EDIT:

With newer release you can just do:

tasks.processResources {}

or

tasks { processResources {} }

generated accessors are "lazy" so it has all the benefits and no downsides.

Heartthrob

This should honestly be the correct answer. You would only need "processResources"(ProcessResources::class) if you weren't in a context where the Java plugin is applied. – Starwort

@Starwort also note what often escapes attention that in configures all tasks with such type for all sourceSets (e.g. also for test and any custom one). Which is a common mistake when people do compileJava {} it only affects JavaCompile task for main sourceSet, so it always should be withType<...> for any type of tasks which has their instances run for different sourceSets – Heartthrob

Answer 3

With updates to the APIs in newer release of the Kotlin DSL and Gradle, you can do something like:

import org.gradle.language.jvm.tasks.ProcessResources

plugins {
  java
}

tasks {
  "processResources"(ProcessResources::class) {
    filesMatching("application.properties") {
      expand(project.properties)
    }
  }
}

And also:

val processResources by tasks.getting(ProcessResources::class) {
  filesMatching("application.properties") {
    expand(project.properties)
  }
}

Mustachio

This is also IMO anti-pattern to get reference to TaskProvider<..> when you are not using that reference. aslo with "newer release" (after time of your anserwer) you can just do tasks.processResources {} or tasks { processResources {} } generated accessors are "lazy" so it has all the benefits and do downsides. – Heartthrob