Conditionally enable event observers in Magento 1.9

Question

I am using multiple event observers in Magento 1.9

From there, I want to conditionally execute other observers. For example, defining the configuration in system.xml to enable or disable execution of observers after certain events.

In config I have this:

<events>
    <event_name>
        <observers>
            <observer_name>
                <type>observer_type</type>
                <class>observer_model</class>
                <method>method_to_call</method>
            </observer_name>
        </observers>
    </event_name>
</events>

Is there any configuration we can use here to enable/disable these observers?

Answer 1

Try this
In config.xml

<controller_action_layout_generate_xml_before>
     <observers>
          <add_new_layout>
              <class>wsafreightcommon/observer</class>
               <method>addNewLayout</method>
          </add_new_layout>
     </observers>
</controller_action_layout_generate_xml_before>

Observer.php

public function addNewLayout($observer){
      $layout = $observer->getEvent()->getLayout();
      $update = $layout->getUpdate();

      $action = $observer->getEvent()->getAction();
      $fullActionName = $action->getFullActionName();

      switch ($fullActionName) {
        case 'adminhtml_sales_order_view':
            $xml = "<reference name='root'><remove name='footer'></remove></reference>";
            $update->addUpdate($xml);
        ...
        break;
      }
//in case you're going to add some conditional (apply these new layout xml on these action or other things, you can modify it by yourself)

//here is the pieces of layout xml you're going to load (you get it from database)


return;}