Debugging Layout XML issues

gistfile1.txt

Source: https://magento.stackexchange.com/questions/95/debugging-layout-xml-loading

You can log the compiled layout XML directives which are used to generate blocks. Create an observer on controller_action_layout_generate_blocks_before, and in the observer method log the update XML from the transported layout object:

public function logCompiledLayout($o)
{
    $req  = Mage::app()->getRequest();
    $info = sprintf(
        "\nRequest: %s\nFull Action Name: %s_%s_%s\nHandles:\n\t%s\nUpdate XML:\n%s",
        $req->getRouteName(),
        $req->getRequestedRouteName(),      //full action name 1/3
        $req->getRequestedControllerName(), //full action name 2/3
        $req->getRequestedActionName(),     //full action name 3/3
        implode("\n\t",$o->getLayout()->getUpdate()->getHandles()),
        $o->getLayout()->getUpdate()->asString()
    );

    // Force logging to var/log/layout.log
    Mage::log($info, Zend_Log::INFO, 'layout.log', true);
}
Output will be similar to:

2013-01-23T16:24:26+00:00 INFO (6): 
Request: cms
Full Action Name: cms_index_index
Handles:
    default
    cms_page
    STORE_default
    THEME_frontend_default_default
    cms_index_index
    page_two_columns_right
    customer_logged_out
Update XML:
<block name="formkey" type="core/template" template="core/formkey.phtml"/>
<label>All Pages</label>
<!-- ... ->

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You can retrieve all the layout handles in your controller by doing this:

var_dump($this->getLayout()->getUpdate()->getHandles());

Or anywhere (as long as the layout has been initialized) using this:

var_dump(Mage::app()->getLayout()->getUpdate()->getHandles());