Working out how Yii2 finds theme resources when using fallbacks

Question

I am using Yii2 and have been reading about theming and theme inheritance; however have some questions:

Consider the following example:

'view' => [
    'theme' => [
        'pathMap' => [
            '@app/views' => [
                '@app/themes/current',
                '@app/themes/default',
            ],
        ],
        'baseUrl' => '@web/themes/current',
        'basePath' => '@webroot/themes/current',
    ],
],

Now, imagine we request the theme file foo; as I understand it this will first be looked for in the following order:

• @app/themes/current/foo.php
• @app/themes/default/foo.php
• @app/views/foo.php

Now imagine foo.php isn't found in the @app/themes/current/ theme, so it would use the file found in @app/themes/default/.

Now, considering the baseUrl and basePath settings I am a little confused how these are used in these situations.

Now, imagine foo.php references an image file inside the file, wouldn't this still attempt to find @web/themes/current/images/myImage.jpg rather than @web/themes/default/images/myImage.jpg?

Answer 1

In this case, basePath is worthless. Because basePath is only applied when pathMap is empty.
basePath is not a fallback, It is a shortcut of pathMap, quick use when you only have one theme.

'pathMap' => [
    '@app/views' => [
         '@app/themes/current/views',
    ],
],

Equivalent to:

'basePath' => '@app/themes/current', 

(Yii understands that folder @app/themes/current/views exist)

baseUrl: It is returned when you call $this->theme->getBaseUrl() in view file. Less worth with multi theme.

About fallback for static files. Theming fallback is not designed for this purpose.

Answer 2

Point your links inside file like this exmaple from docs:

$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');

It will get file from current theme directory.