Question

Small part of Page.xml:

<layout version="0.1.0">
     ....
      <default translate="label" module="page">
        <label>All Pages</label>
        <block type="page/html" name="root" output="toHtml" template="page/2columns-left.phtml">
             <block type="page/html_header" name="header" as="header" /> <!-- work -->
             <block type="page/html_wrapper" name="u.Top.Menu" as="u_Top_Menu" translate="label"> <!-- doesn't work -->
                    <label>top menu</label>
                    <action method="setElementTagName"><value>div</value></action>
                    <action method="setElementClass"><value>sub-menu</value></action>
             </block>
         ...
         </block>
....

And in the 2columns-left.phtml output it:

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

But it always retuns empty value. I’m confused here a bit. What I’m doing wrong here?

Answer 1

This is what happens when you forget to add the children block to the html wrapper block. Look at this block class source code:

class Mage_Page_Block_Html_Wrapper extends Mage_Core_Block_Abstract
{
    /**
     * Whether block should render its content if there are no children (no)
     * @var bool
     */
    protected $_dependsOnChildren = true;

    /**
     * Render the wrapper element html
     * Supports different optional parameters, set in data by keys:
     * - element_tag_name (div by default)
     * - element_id
     * - element_class
     * - element_other_attributes
     *
     * Renders all children inside the element.
     *
     * @return string
     */
    protected function _toHtml()
    {
        $html = empty($this->_children) ? '' : trim($this->getChildHtml('', true, true));
        if ($this->_dependsOnChildren && empty($html)) {
            return '';
        }

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