Magento – CMS XML Handles for Layout Updates

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I've had a few scenarios where I've tried to use the cms handles to update a cms page's layout. For example I was trying to use the cms_index_index handle referencing root and setting the page template. This failed and I had to make this layout update via the admin system directly on the homepage cms page display settings.

I've also tried to add a block to reference left using the cms_page handle. Again this failed and I had to implement the layout update via the admin system.

I've read that you can't assign a root template to cms pages. Is that correct and can anyone explain why?

I also wondered if there was a way to enable cms handles to use the standard references such as left, right, root etc? I seem to be able to reference things like head and content just fine.

Best Answer

Why changing the root template doesn't work

Both

Mage_Cms_IndexController::indexAction()

and

Mage_Cms_IndexController::viewAction()

which are responsible for displaying the default homepage and a CMS page respectively call a helper:

Mage::helper('cms/page')->renderPage($this, $pageId)

If you jump into the helper (located at app/code/core/Mage/Cms/Helper/Page.php) and follow renderPage() to the protected method _renderPage() you'll see that Magento is checking two times for a root template (Magento CE 1.7.0.2):

if ($page->getRootTemplate()) {
    $handle = ($page->getCustomRootTemplate()
                && $page->getCustomRootTemplate() != 'empty'
                && $inRange) ? $page->getCustomRootTemplate() : $page->getRootTemplate();
    $action->getLayout()->helper('page/layout')->applyHandle($handle);     
}

and

if ($page->getRootTemplate()) {
    $action->getLayout()->helper('page/layout')
        ->applyTemplate($page->getRootTemplate());
}

Both calls happen after layout handles like "cms_page" and the like are processed, so you are out of luck here.

What you can do to change the root template

There is an event cms_page_render which you can use for adding your own XML layout handle on CMS pages. Create your own extension (I'll spare some details here) and configure the event observer in your config.xml:

<?xml version="1.0"?>
<config>
    <modules>
        <Emzee_Cms>
            <version>0.0.1</version>
        </Emzee_Cms>
    </modules>

    <global>
        <events>
            <cms_page_render>
                <observers>
                    <emzee_cms_page_render>
                        <class>emzee_cms/observer</class>
                        <method>cms_page_render</method>
                    </emzee_cms_page_render>
                </observers>
            </cms_page_render>
        </events>
        <models>
            <emzee_cms>
                <class>Emzee_Cms_Model</class>
            </emzee_cms>
        </models>
    </global>
</config>

Add your event observer:

<?php

class Emzee_Cms_Model_Observer
{
    public function cms_page_render(Varien_Event_Observer $observer)
    {
        $action = $observer->getEvent()->getControllerAction();

        $actionName = strtolower($action->getFullActionName());
        $action->getLayout()->getUpdate()
            ->addHandle($actionName . '_after');
        return $this;
    }
}

Finally, add your new layout XML handle (e.g. in your local.xml):

<?xml version="1.0"?>
<layout version="0.1.0">
    <cms_index_index_after>
        <reference name="root">
            <action method="setTemplate"><template>page/1column.phtml</template></action>
        </reference>
    </cms_index_index_after>
</layout>

You can use this method as well to add a cms_page_view_after handle or create page specific handles as cms_page_render passes the $page object to your observer.

Why you can't add a block to the 'reference left'

Are you sure that the template you're using has a left column? This question may sound silly but the default "2 columns with right bar" layout for example only offers a 'content' and a 'right' area. I can add blocks to the right column using cms_page without problems so this could be the problem.

In general, you can only easily add blocks to references and echo them if

  • the chosen root template uses the block you're referencing (see app/design/frontend/base/default/template/page/*.phtml) and
  • the block you're referencing either is of type core/text_list, calls $this->getChildhtml() without arguments or does something else to echo all child blocks.

Without further details, I can't tell you why your blocks are not echo'd in the left or right column.

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