Providing your own URL rules at runtime in YII framework

When you are developing an application with pluggable module architecture, you most likely
need to somehow inject your module-specific rules into an existing application.
Getting ready
1. Set up a new application using yiic webapp.
2. Add .htaccess, shown in official URL Management guide to your webroot.
3. Add 'showScriptName' => false to your URL manager configuration.
4. Generate the page module using Gii.
5. Don't forget to add your new module to the modules list in your application
configuration.
How to do it...
1. Create ModuleUrlManager.php in your protected/components directory with
the following code inside:
<?php
class ModuleUrlManager
{
static function collectRules()
{
if(!empty(Yii::app()->modules))
{
foreach(Yii::app()->modules as $moduleName => $config)
{
$module = Yii::app()->getModule($moduleName);
if(!empty($module->urlRules))
{
Yii::app()->getUrlManager()->addRules
($module->urlRules);
}
}
}
return true;
}
}
2. In your application configuration, add the following line:
'onBeginRequest' => array('ModuleUrlManager', 'collectRules'),
3. Now, in your page module, you can add custom rules. To do so, open PageModule.
php and add:
public $urlRules = array(
'test' => 'page/default/index',
);
4. To test if it works, open your browser and go to http://example.com/test.
This is the view content for action "index". The action belongs to the controller
"DefaultController" in the "page" module.
5. You still can override URL rules from your main application configuration file. So, what
you specify in module's urlRules is used only when the main application rules are
not matching.
Let's review the ModuleUrlManager::collectRules method.
If there are modules defined in our application, then we are checking if urlRules public
property exists. If it does, then there are some rules defined in the module and they are
added using CUrlManager::addRules.
CUrlManager::addRules description says "In order to make the new rules effective, this
method must be called before CWebApplication::processRequest".
Now, let's check how our application works. In our index.php, we have the following line:
Yii::createWebApplication($config)->run();
After being initialized with configuration, we are calling CWebApplication::run():
public function run()
{
if($this->hasEventHandler('onBeginRequest'))
$this->onBeginRequest(new CEvent($this));
$this->processRequest();
if($this->hasEventHandler('onEndRequest'))
$this->onEndRequest(new CEvent($this));
}
As we can see, there is an onBeginRequest event raised just before calling
processRequest. That is why we are attaching our class method to it.
There's more...
As instantiating all application modules on every request is not good for performance, it is
good to cache module rules. Caching strategy can vary depending on your application. Let's
implement a simple one:
<?php
class ModuleUrlManager
{
static function collectRules()
{
if(!empty(Yii::app()->modules))
{
$cache = Yii::app()->getCache();
foreach(Yii::app()->modules as $moduleName => $config)
{
$urlRules = false;
if($cache)
$urlRules = $cache->get('module.urls.'.$moduleName);
if($urlRules===false){
$urlRules = array();
$module = Yii::app()->getModule($moduleName);
if(isset($module->urlRules))
$urlRules = $module->urlRules;
if($cache)
$cache->set('module.urls.'.$moduleName, $urlRules);
}
if(!empty($urlRules))
Yii::app()->getUrlManager()->addRules($urlRules);
}
}
return true;
}
}
This implementation caches URL rules per module. So, adding new modules is not
a problem but changing existing ones requires you to flush cache manually using
Yii::app()->cache->flush().