Magento - Checking if a module is installed?

I have a small piece of code in a template file that开发者_运维问答 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?

---

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.

---

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.";
}   

---

Another way to find if a module is installed but disabled is with:

if (Mage::getStoreConfigFlag('advanced/modules_disable_output/Mage_Paypal')) {
    echo "Paypal module is installed";
}

Edit
Have just realised a version of this - using the little known ifconfig - could show a block only if another module is disabled. eg.

<layout>
    <default>
        <reference name="content">
            <block ifconfig="advanced/modules_disable_output/Mage_Paypal" type="core/template" template="sorry/this/is/unavailable.phtml" />
        </reference>
    </default>
</layout>

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You can check if a module exists on installation using this snippet Mage::getConfig()->getNode('modules/Mage_Paypal') returns FALSE if does not exist

---

in the declaration of your module, try adding a depends element, like on this page. This will probably raise an exception, which you could handle with a try/catch block.

---

In any class, model, controller or even PHTML you can call and it will work.

Data.php

class Company_Module_Helper_Data extends Mage_Core_Helper_Abstract 
{ 
  const XML_PATH_GEN_ENABLE = 'Section/Group/Field';
  public function isEnable() 
  {
    return Mage::getStoreConfigFlag(XML_PATH_GEN_ENABLE,Mage::app()->getStore()->getId());
  } 
}

You can call using below code Mage::helper('module_name')->isEnable()

Your config file is like

config.xml

<global>
  <helpers> 
    <module_name> 
      <class>Company_Module_Helper</class> 
    </module_name> 
  </helpers>
  // Another Necessary Code for this extension
</global>