Difference Between and in Magento Layout

blockslayout

My current understanding of defining layout blocks is that if I do:

<block type="core/template" name="a.b" as="aB" template="some.phtml">
    <block type="x/y" name="c.d" as="cD" />
</block>

then I've added c.d as a child block of a.b, and from within some.phtml I can call $this->getChildHtml('cD'); to ask c.d to render its output at that position in the template.

I was looking around in catalog.xml, and I've just come across the syntax:

<action method="append"><block>block.name</block></action>

so I followed it to see what's different from the previous method:

public function append($block, $alias = '')
{
    $this->insert($block, '', true, $alias);
    return $this;
}

....

public function insert($block, $siblingName = '', $after = false, $alias = '')

append implies ordering the child block at the end of the parent block, but I could have easily done that with an after="-" parameter in the first method.

So, what's the difference between these two methods of adding a child block to a parent block?

Best Answer

append appends an existing block that is referenced by name, to a new parent. It can be used to move a block to another location or to duplicate it.

<block> always creates a new block.

Related Solutions

Difference Between and in Magento Layout

<remove name="" /> operates in the global block scope of Mage_Core_Model_Layout. These are collected in Mage_Core_Model_Layout::generateXml() and used to prevent the block with the specified name from even being instantiated. Also, any child blocks declared for a <remove />ed block will also not be instantiated.

<action method="" /> a.k.a Mage_Core_Block_Abstract::unsetChild() is a block-level method which de-lists the indicated child block (by alias, not by name) from the parent block instance on which the action is being called. This most often results in the block "disappearing" from the rendered output, even though the block instance is still created. Used in combination with the ::append() or ::insert() methods, it is used to perform a "move".

Magento 1.9.0.1 – How to Add a Block to an Existing Tab Programmatically

You can try this. I didn't test this code.

class My_Details_Block_Product extends Mage_Core_Block_Template
{
    protected $_template = 'details/product_details.phtml';

    protected function _prepareLayout() {
        if ($addToTabBlock = $this->getLayout()->getBlock('product.description')) {

            //sets this block as child to description block
            $addToTabBlock->setChild( 'my.custom.block',$this->getLayout()->createBlock( $this,'my.custom.block',array('template' => 'details/product_details.phtml')));
        }
        return parent::_prepareLayout();
    }
}

You may need to call this block in description.phtml as like this

<div><?php echo $this->getChildHtml('my.custom.block');  ?> </div>

in the desired position

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