Magento - Checking if a module is installed?

Question

I have a small piece of code in a template file that I ONLY want to run if a certain module is installed. I found the below code, which you can use to find if a module is active, but I want to know if a module is installed.

$modules = Mage::getConfig()->getNode('modules')->children();
$modulesArray = (array)$modules;

if($modulesArray['Mage_Paypal']->is('active')) {
    echo "Paypal module is active.";
} else {
    echo "Paypal module is not active.";
}

I'm thinking I could maybe get a list of names of all the modules that are installed, and then use

if (stristr($modulelist, 'Name_Extension'))

to show my code only if the referenced extension is installed.

Anyone any ideas how to do that? Or any better solutions?

Answer 1

There's a core helper for that:

Mage::helper('core')->isModuleEnabled('MyCompany_MyModule');

It's in Mage_Core_Helper_Abstract.

There's also a isModuleOutputEnabled() method to check if output of module is disabled in System -> Configuration -> Advanced -> Disable Modules Output.

Answer 2

Try this:

$modules = Mage::getConfig()->getNode('modules')->children();
$modulesArray = (array)$modules;

if(isset($modulesArray['Mage_Paypal'])) {
    echo "Paypal module exists.";
} else {
    echo "Paypal module doesn't exist.";
}