Copying multiple directories in a single Gradle task with up-to-date checking

How to write a single Gradle task to copy multiple directories and still use up-to-date checking..

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Suppose you wanted to copy several directories of Twitter Bootstrap styling and JavaScript, each one into a different destination directory. And you wanted to use Gradle’s up-to-date checking with defined inputs and outputs to only run the task when needed, i.e. when a task input or output changed. Gradle has a built-in Copy task type, but that only supports a single destination directory. Now if you didn’t want to define a separate Gradle task for each directory, how can you copy multiple directories in a single Gradle task?

Maybe the first way you find is to use Gradle’s append syntax to define the task.

task copyBootstrap << {
    copy {
        from "${bowerComponentsDir}/bootstrap-sass-official/assets/fonts"
        into 'theme/fonts/vendor'
    }
    copy {
        from "${bowerComponentsDir}/jquery/dist"
        into 'theme/javascripts/vendor/jquery'
    }
    copy {
        from "${bowerComponentsDir}/bootstrap/dist/js"
        into 'theme/javascripts/vendor/bootstrap'
    }
    copy {
        from "${bowerComponentsDir}/bootstrap-sass-official/assets/stylesheets"
        into 'theme/sass/vendor/bootstrap'
    }
}

But if you try to define task inputs and outputs with the above task type, Gradle will warn you in the console that up-to-date checking wasn’t supported in this task.

Don’t despair, there is a solution! You can use a doLast closure inside the Gradle task to be able to copy multiple directories and still use up-to-date checking. This is what the resulting task might look like with up-to-date checking enabled:

task copyBootstrap {
    inputs.file 'bower.json'
    inputs.dir 'bower_components/bootstrap'
    inputs.dir 'bower_components/bootstrap-sass-official'

    outputs.dir 'theme/fonts/vendor/bootstrap'
    outputs.dir 'theme/javascripts/vendor/jquery'
    outputs.dir 'theme/javascripts/vendor/bootstrap'
    outputs.dir 'theme/sass/vendor/bootstrap'

    doLast {
        copy {
            from "${bowerComponentsDir}/bootstrap-sass-official/assets/fonts"
            into 'theme/fonts/vendor'
        }
        copy {
            from "${bowerComponentsDir}/jquery/dist"
            into 'theme/javascripts/vendor/jquery'
        }
        copy {
            from "${bowerComponentsDir}/bootstrap/dist/js"
            into 'theme/javascripts/vendor/bootstrap'
        }
        copy {
            from "${bowerComponentsDir}/bootstrap-sass-official/assets/stylesheets"
            into 'theme/sass/vendor/bootstrap'
        }
    }
}

Now you have a single task that will copy multiple directories and will only run when one of those defined inputs or outputs changes!

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