Magento – Get Attribute model by attribute_code in Magento

The following will work:

foreach($filters as $_filter)
{
    $attributeModel = $_filter->getAttributeModel();
    if($attributeModel) {
        echo $attributeModel->getAttributeCode();
    }
}

The key here is to check that the filter is actually an attribute as some aren't (most commonly categories) and these types of filters obviously won't have an attribute code.

I edited your script and it worked fine for me, I can see new attribute in backed now.

Replace this:

$installer = $this;
$installer->startSetup();

$setup = new Mage_Eav_Model_Entity_Setup('core_setup');

With this:

$setup = new Mage_Eav_Model_Entity_Setup('core_setup');
$setup->startSetup();