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Application Assets

Asset files like CSS or JavaScript are resources which you have to integrate in your web project but organize them in a "package" like folders, called Asset Bundles. Assets are based on Yii 2 Asset Bundles you may read more detailed information about. The LUYA assets describe just another way of including them into you project.

Below, an example class of an asset where files are located in @app/resources and includes the css/styles.css into the view files where the asset is loaded.

namespace app\assets;

class MyTestAsset extends \luya\web\Asset
    public $sourcePath = '@app/resources';
    public $css = [

From the example above the CSS file style.css would be looked up in the location @app/resources/css/styles.

In a project context, we recommend to not store images inside the asset sources. Images should stored in the public_html folder and you can access them in the view with src="<?= $this->publicHtml; ?>/myimage.jpg".

Using the Asset

To use an asset bundle, register it with a view by calling the yii\web\AssetBundle -> register() method. E. g. in a view template you can register an asset bundle like the following:

use app\assets\AppAsset;
AppAsset::register($this);  // $this represents the view object

The yii\web\AssetBundle::register() method returns an asset bundle object containing the information about the published assets, such as basePath or baseUrl.

If you are registering an asset bundle in other places, you should provide the needed view object. E. g. to register an asset bundle in a widget class you can get the view object by $this->view.

When an asset bundle is registered with a view, behind the scenes Yii will register all its dependent asset bundles. And if an asset bundle is located in a directory inaccessible through the Web, it will be published to a Web directory. Only when the view renders a page, it will generate link and script tags for the CSS and JavaScript files listed in the registered bundles. The order of these tags is determined by the dependencies among the registered bundles and the order of the assets listed in the yii\web\AssetBundle -> $css and yii\web\AssetBundle -> $js properties.

Publish Options

To ensure a minimal footprint and to avoid issues with node packages inside the resource folder, it's recommended to manually select the folders which should be published. E. g. in the LUYA kickstarter project you'll find a bootstrap and a css folder in the publish options:

public $publishOptions = [
    'only' => [

Or you can do also the opposite of this behavior by select which folder should not be copied within the assets folder. To do so configure the except property:

public $publishOptions = [
    'except' => [

Patterns ending with '/' apply to directory paths only, and patterns not ending with '/' apply to file paths only. For example, '/a/b' matches all file paths ending with '/a/b'; and '.svn/' matches directory paths ending with '.svn'.

Accessing the asset path

Sometimes you may want to access the folder with the asset files, therefore you need to retrieve the base URL of the asset which as the actual path of the folder in the filesystem which is in the public_html/assets/$HASH_NUMBER.

Run the getBundle() method inside your view file for the registered assetManager in the view object:

$myAsset = $this->assetManager->getBundle('\\app\\assets\\MyTestAsset');

echo $myAsset->baseUrl;