Ajax request issue on adminhtml controller

Question

This is my prototype code:

new Ajax.Request(BASE_URL + 'hospitals', {
        method: 'post',
        postBody:'store_id='+store_id+'&isAjax=1',
        onSuccess: successFunc,
        onFailure:  failureFunc
    });

This is my controller:

class Mynamespace_Mymodul_Adminhtml_HospitalsController extends Mage_Adminhtml_Controller_Action
{
    public function indexAction()
    {
      var_dump($this->getRequest()->getPost('store_id')); exit();
    }
}

The url it set correct. The post parameters are correct and they are sent. But i the response is this:

{"error":true,"message":"Invalid Form Key. Please refresh the page."} 

What should I do ?

Answer 1

All admin URLs should have a key that is generated based on the action controller and action name and some random session key.
You cannot simply do a call to ROOT/hospitals/.
You need something like this ROOT/module/controller/action/key/{some hash key here}/?other=params.

I assume you are making the ajax call from a template file.
You should do the call like this:

<?php $url = $this->getUrl('hospitals');?><!-- this will generate the proper url-->
<script type="text/javascript">
    new Ajax.Request('<?php echo $url?>', {
        method: 'post',
        postBody:'store_id='+store_id+'&isAjax=1',
        onSuccess: successFunc,
        onFailure:  failureFunc
    });
</script>