Programmatically set and unset event triggering for a custom module

Question

So here is the scenario that I need to achieve. I have a custom module. In it's controller, I am setting a cookie when some conditions are met. I need to check the status of this cookie if any other url request is made through an observer (event using is controller_action_predispatch). When some conditions are met, I will delete this cookie and then I don't want to trigger the event any more (or till next time when the cookie sets through my controller.).

An example shown below. My custom controller looks like this

File: app\code\local\Namespace\Module\controllers\CustomController.php

public function someAction()
{
      if (<some_condition_met>) {
          Mage::getModel('core/cookie')->set('cookiename', 'value', 7200);
          $this->activateObserver($eventname, $modulename, $methodname); // I need this. Later for all action it should observer the event that is specified inside `activateObserver()`
      }
}

activateObserver() will starts event triggering. Now onwards, for every action, it should observe to my custom obsever method.

Now my observer method looks like this.

File : app\code\local\Namespace\Module\Model\Observer.php

public function myObserverMethod($observer)
{
        if (<some_condition_met>) {
             Mage::getModel('core/cookie')->delete('cookiename');
             $this->deactivateObserver($eventname, $modulename); //this should deactivate event observation. Now onwards I dont need to observe this event
        }
}

Now here deactivateObserver() deactivate event triggering from my module.

Why I need this ?

This is because, I am observing to controller_action_predispatch. I just want to observe this event during the life time of my cookie. This cookies life time is 2 hours maximum. Since the event that I am observing occurs for every action, it would be definitely a burden and I need to avoid this.

Is it possible in Magento ? Share your thoughts.

Answer 1

This is not possible - the event will be fired each time for every module including yours. You can only programmatically deactivate the event observer completely, but this is not what you are after.

So the thing you would normally do is to directly check in your observer method if the cookie is set and if it is not set, return instantly:

public function myObserverMethod($observer)
{
    if (<cookie_not_set>) {
        return;
    }
    // do whatever you need to do
}

I understand your point that you do not want to do it like that, because the event is fired so often. The only solution I see here is that you could potentially use a more specific event which is not fired that often like controller_action_predispatch_cms or controller_action_predispatch_cms_index_index. Have a look at the event dispatching code here in order to find a suitable event.

Answer 2

I think this can be another solution if you set your observer as dispatched once it is triggered, and do nothing once it is already dispatched, this is basically regarding unregistering an observer:

public function updateCustomer($observer){
    if (Mage::registry('my_event_was_dispatched') == 1){//do nothing if the event was dispatched
        return $this;
    }
    //your code here
    Mage::register('my_event_was_dispatched', 1);//mark the event as dispatched.
}

Check this reference URL, this may be another alternate.

Answer 3

It's possible to disable an entire event in your module config:

...
<events>
    <some_event_observer>
        <observers>
            <unique_string>
                <type>disabled</type>
            </unique_string>
        </observers>
    </some_event_observer>
</events>
...

And you can also achieve this on the fly but you wouldn't want to anyway as it would mean that event wouldn't fire at all so any other observers attached to it won't fire either. As far as I know there isn't anything like this to disable just a single observer so if you wanted that, you would probably have to hack around in the config object.

Doesn't strike me as a great idea to be honest and not something I have ever tried to do so I can't really give you any pointers. If you are not happy using an observer which fires every request and you have to use this observer (i.e. you can't do something more controller/action specific) then the best you can do is look for an alternative way to achieve whatever it is your end goal is, there is almost definitely a better solution.

Answer 4

I am agree with @Simon but
i suggest that you have do this a global flag.for global flag you need to use Mage::registry()

Step1: Create global registry variable when you have goes to someAction set it value to 1;

Step2: when events controller_action_predispatch is trigger and then condition is match for delete and check registry variable exit and it value is 1

Step3: then this registry variable makes to 0;

it just a concept basic