Cascading Filesystem

The Kohana filesystem is a hierarchy of similar directory structures that cascade. The hierarchy in Kohana (used when a file is loaded by Kohana::find_file) is in the following order:

  1. Application Path
    Defined as APPPATH in index.php. The default value is application.

  2. Module Paths
    This is set as an associative array using Kohana::modules in APPPATH/bootstrap.php. Each of the values of the array will be searched in the order that the modules are defined.

  3. System Path
    Defined as SYSPATH in index.php. The default value is system. All of the main or "core" files and classes are defined here.

Files that are in directories higher up the include path order take precedence over files of the same name lower down the order, which makes it is possible to overload any file by placing a file with the same name in a "higher" directory:

Cascading Filesystem Infographic

This image is only shows certain files, but we can use it to illustrate some examples of the cascading filesystem:

  • If Kohana catches an error, it would display the kohana/error.php view, So it would call Kohana::find_file('views', 'kohana/error'). This would return application/views/kohana/error.php because it takes precidence over system/views/kohana/error.php. By doing this we can change the error view without editing the system folder.

  • If we used View::factory('welcome') it would call Kohana::find_file('views','welcome') which would return application/views/welcome.php because it takes precidence over modules/common/views/welcome.php. By doing this, you can overwrite things in a module without editing the modules files.

  • If use the Cookie class, Kohana::auto_load will call Kohana::find_file('classes', 'Cookie') which will return application/classes/Cookie.php. Assuming Cookie extends Kohana_Cookie, the autoloader would then call Kohana::find_file('classes','Kohana/Cookie') which will return system/classes/Kohana/Cookie.php because that file does not exist anywhere higher in the cascade. This is an example of transparent extension.

  • If you used View::factory('user') it would call Kohana::find_file('views','user') which would return modules/common/views/user.php.

  • If we wanted to change something in config/database.php we could copy the file to application/config/database.php and make the changes there. Keep in mind that config files are merged rather than overwritten by the cascade.

Types of Files

The top level directories of the application, module, and system paths have the following default directories:

All classes that you want to autoload should be stored here. This includes controllers, models, and all other classes. All classes must follow the class naming conventions including matching the case of the class i.e. Kohana_Cookie should be stored in classes/Kohana/Cookie.php and not classes/kohana/cookie.php.
Configuration files return an associative array of options that can be loaded using Kohana::$config. Config files are merged rather than overwritten by the cascade. See config files for more information.
Translation files return an associative array of strings. Translation is done using the __() method. To translate "Hello, world!" into Spanish, you would call __('Hello, world!') with I18n::$lang set to "es-es". I18n files are merged rather than overwritten by the cascade. See I18n files for more information.
Message files return an associative array of strings that can be loaded using Kohana::message. Messages and i18n files differ in that messages are not translated, but always written in the default language and referred to by a single key. Message files are merged rather than overwritten by the cascade. See message files for more information.
Views are plain PHP files which are used to generate HTML or other output. The view file is loaded into a View object and assigned variables, which it then converts into an HTML fragment. Multiple views can be used within each other. See views for more information.
You can include any other folders in your cascading filesystem. Examples include, but are not limited to, guide, vendor, media, whatever you want. For example, to find media/logo.png in the cascading filesystem you would call Kohana::find_file('media','logo','png').

Finding Files

The path to any file within the filesystem can be found by calling Kohana::find_file:

// Find the full path to "classes/Cookie.php"
$path = Kohana::find_file('classes', 'Cookie');

// Find the full path to "views/user/login.php"
$path = Kohana::find_file('views', 'user/login');

If the file doesn't have a .php extension, pass the extension as the third param.

// Find the full path to "guide/"
$path = Kohana::find_file('guide', 'menu', 'md');

// If $name is "2000-01-01-first-post" this would look for "posts/2000-01-01-first-post.textile"
$path = Kohana::find_file('posts', $name, '.textile');

Note: If caching is enabled than Kohana::find_file() saves results for one minute (defined in Kohana::$cache_life). During cache lifetime no new file will be found in the cascading file system and deleted files will still be returned.

Vendor Extensions

We call extensions or external libraries that are not specific to Kohana "vendor" extensions, and they go in the vendor folder, either in application or in a module. Because these libraries do not follow Kohana's file naming conventions, they cannot be autoloaded by Kohana, so you will have to manually included them. Some examples of vendor libraries are Markdown, DOMPDF, Mustache and Swiftmailer.

For example, if you wanted to use DOMPDF, you would copy it to application/vendor/dompdf and include the DOMPDF autoloading class. It can be useful to do this in a controller's before method, as part of a module's init.php, or the contstructor of a singleton class.

require Kohana::find_file('vendor', 'dompdf/dompdf/dompdf_config','inc');

Now you can use DOMPDF without loading any more files:

$pdf = new DOMPDF;

If you want to convert views into PDFs using DOMPDF, try the PDFView module.