Magento Request - Frontend or Backend?

Question

How can I tell if the current request is for a backend or frontend page? This check will be done inside an observer, so I do have access to the request object if that helps

Answer 1

I like beep logic's answer - it makes sense in the context of observers. I also like Alan's point that there is no way to know the admin state in all contexts, which is a function of "the admin" being a state which is entered after the app and front controller are initialized.

Magento's admin state is effectively created from the control dispatching to an admin action controller; see Mage_Adminhtml_Controller_Action::preDispatch(). This is the method which fires the adminhtml_controller_action_predispatch_start event, which is consumed by Mage_Adminhtml_Model_Observer::bindStore(), which is where the admin store is initially "set". In fact, the observer configuration areas (adminhtml vs frontend) "works" because of the main action controller class - see Mage_Core_Controller_Varien_Action::preDispatch(), specifically Mage::app()->loadArea($this->getLayout()->getArea()); - just note that the layout object has its area information set in the adminhtml predispatch.

No matter how you slice it, the admin behavior on which we rely in so many contexts - even something as high-level as the event observer system - relies on the command control structure.

  
  
    
      
        
          
            singleton
            mynamespace_mymodule/observer
            adminPrepareLayoutAfter
          
        
      
    
  
  
    
      
        
          
            singleton
            mynamespace_mymodule/observer
            frontendPrepareLayoutAfter
          
        
      
    
  

In your observer definition:

class Mynamepace_Mymodule_Model_Observer
{
    public function adminPrepareLayoutAfter()
    {
        $this->_prepareLayoutAfter('admin');
    }

    public function frontendPrepareLayoutAfter()
    {
        $this->_prepareLayoutAfter('frontend');
    }

    protected function _prepareLayoutAfter($area)
    {
        switch($area){
           case 'admin':
               // do admin things
               break;

           case 'frontend':
               // do frontend things
               break;

           default:
               // i'm a moron
        }
    }
}

tl;dr: Use an observer, even use the same observer model, but pass in the context by specifying a different calling method.

HTH.

edit: added example code using beep logic's config as a starting point