how can I append custom block to head in adminhtml controller action

Question

I was trying to add a block to the head in magento backend for a specific controller action.

public function updateAction(){

    $block = $this->getLayout()->createBlock(
        'Mage_Core_Block_Template',
        'namespace_update_form_head_data',
        array(
            'template' => 'namespace/update/head/data.phtml'
        )
    );

    /**
     * @var Mage_Adminhtml_Block_Page_Head
     */
    $head =$this->getLayout()->getBlock('head');
    $head->append($block);
}

However nothing is output in the head

If I use getBlock('content') or getBlock('js') instead of getBlock('head') for example it works fine but outputs the text at the content area as expected or at the end of body.

If I try $head->addCss() or $head->addJs() they both work fine too and I can add specific js or css files but I can't append a block template.

Could anyone explain to me why it's not loading the block and how to properly load it if possible?

Thanks in advance

Answer 1

Admin head block won't automatically render and display all its children.

You need to go to head template app/design/adminhtml/default/default/template/page/head.phtml and add:

<?php echo $this->getChildHtml('namespace_update_form_head_data') ?>