Theming is a way to replace a set of views with another without the need of touching the original view rendering code. You can use theming to systematically change the look and feel of an application.
To use theming, you should configure the [[yii\base\View::theme|theme]] property of the
view application component. The property configures a [[yii\base\Theme]] object which governs how view files are being replaced. You should mainly specify the following properties of [[yii\base\Theme]]:
- [[yii\base\Theme::basePath]]: specifies the base directory that contains the themed resources (CSS, JS, images, etc.)
- [[yii\base\Theme::baseUrl]]: specifies the base URL of the themed resources.
- [[yii\base\Theme::pathMap]]: specifies the replacement rules of view files. More details will be given in the following subsections.
For example, if you call
SiteController, you will be rendering the view file
@app/views/site/about.php. However, if you enable theming in the following application configuration, the view file
@app/themes/basic/site/about.php will be rendered, instead.
return [ 'components' => [ 'view' => [ 'theme' => [ 'basePath' => '@app/themes/basic', 'baseUrl' => '@web/themes/basic', 'pathMap' => [ '@app/views' => '@app/themes/basic', ], ], ], ], ];
Info: Path aliases are supported by themes. When doing view replacement, path aliases will be turned into the actual file paths or URLs.
You can access the [[yii\base\Theme]] object through the [[yii\base\View::theme]] property. For example, in a view file, you can write the following code because
$this refers to the view object:
$theme = $this->theme; // returns: $theme->baseUrl . '/img/logo.gif' $url = $theme->getUrl('img/logo.gif'); // returns: $theme->basePath . '/img/logo.gif' $file = $theme->getPath('img/logo.gif');
The [[yii\base\Theme::pathMap]] property governs how view files should be replaced. It takes an array of key-value pairs, where the keys are the original view paths to be replaced and the values are the corresponding themed view paths. The replacement is based on partial match: if a view path starts with any key in the [[yii\base\Theme::pathMap|pathMap]] array, that matching part will be replaced with the corresponding array value. Using the above configuration example, because
@app/views/site/about.php partially matches the key
@app/views, it will be replaced as
In order to theme modules, [[yii\base\Theme::pathMap]] can be configured like the following:
'pathMap' => [ '@app/views' => '@app/themes/basic', '@app/modules' => '@app/themes/basic/modules', // <-- !!! ],
It will allow you to theme
In order to theme widgets, you can configure [[yii\base\Theme::pathMap]] in the following way:
'pathMap' => [ '@app/views' => '@app/themes/basic', '@app/widgets' => '@app/themes/basic/widgets', // <-- !!! ],
This will allow you to theme
Sometimes you may want to define a basic theme which contains a basic look and feel of the application, and then based on the current holiday, you may want to vary the look and feel slightly. You can achieve this goal using theme inheritance which is done by mapping a single view path to multiple targets. For example,
'pathMap' => [ '@app/views' => [ '@app/themes/christmas', '@app/themes/basic', ], ]
In this case, the view
@app/views/site/index.php would be themed as either
@app/themes/basic/site/index.php, depending on which themed file exists. If both themed files exist, the first one will take precedence. In practice, you would keep most themed view files in
@app/themes/basic and customize some of them in