Remove left sidebar through coding

Question

How to remove the left sidebar based on some condition written in block? I have to use the same layout xml file. Based on a condition, need to remove a block through coding. section need to be removed:

 <reference name="left">
   <block type="catalog/layer_view" name="catalog.leftnav" before="-" template="catalog/layer/view.phtml"/>
 </reference>

I tried with below code.

Mage::app()->getLayout()->unsetBlock('left.catalog.leftnav');

I didn't get any error but left sidebar still there. can anyone help me? Thanks.

1. I cant access controller. If i have access for controller, then i can easily do in layout rendering section. So i added my work as module and created block. Now I need to change layout / remove left sidebar.

2. Or is It possible to change the layout xml from block? Because i have condition statement in block. so i can choose the layout based on the condition.

Can anyone help me to fix this? Thanks

Answer 1

If you do not want to use an observer what you could do is rewrite the block Mage_Catalog_Block_Layer_View and override the function _toHtml so that it performs the conditional check you want.

protected function _toHtml() {
    if (your conditional check) {
        return '';
    }
    return parent::_toHtml();
}

Answer 2

you can try to listen some event like controller_action_layout_load_before and you will get layout object like

$update = $observer->getEvent()->getLayout()->getUpdate();

now you can remove/unset the block