grunt-if-missing

Conditionally run a task if any of its destination files do not exist.

Why?

I used grunt-curl to download an external dependency. That task would get executed often, but the file did not need to get downloaded again if it already existed. With this plugin I am able to execute a task if it is currently missing its "dest" file.

Another project uses a git submodule as a dependency and needs to build it once before using it. This plugin is able to determine if a file exists and will use grunt-run to start a build that will generate the necessary files. Once they exist they won't need to get rebuilt.

Usage

This plugin requires Grunt ~0.4.1. If you have not used Grunt before, make sure to read its Getting Started guide to learn about gruntfile.js and installing plugins.

Installation is easy and identical to other plugins:

npm install grunt-if-missing --save-dev

Once installed, you might have it loaded automatically if you use load-grunt-tasks, or you can manually load it with this line:

grunt.loadNpmTasks('grunt-if-missing');

Configuration

There is no special configuration necessary. Like the newer plugin, you will just add if-missing as the first argument when running other tasks. Let's use a configuration that uses grunt-curl as an example.

grunt.initConfig({
    curl: {
        angular: {
            dest: "3rd_party/angular-1.2.14.zip",
            src: "http://code.angularjs.org/1.2.14/angular-1.2.14.zip"
        }
    }
});
grunt.loadNpmTasks('grunt-curl');
grunt.loadNpmTasks('grunt-if-missing');
grunt.registerTask('get-dependencies', [
    'if-missing:curl:angular'
]);

By using just this configuration, you can now download your Angular dependency by issuing grunt curl. It would normally download it every time, even if it already existed. grunt get-dependencies will download the file only if it does not already exist at 3rd_party/angular-1.2.14.zip.

This task is only able to be used with other tasks that have dest defined or specify a destination filename in any of the standard methods.

Development

If you want to work on this library, you need to check out the repository and run npm install to get the dependencies.

Tests are always included. Make sure tests cover your changes. To run the current tests, just use npm test or grunt test (they will run the same test suite).

License

This software is licensed under an MIT license with an additional non-advertising clause.