Fatal error with Custom Magento Module on one server but not the other

Question

I am creating my own custom module in Magento and during testing on a Litespeed server (PHP v5.2.14) I am getting a Fatal Error: Call to a member function batch() on a non-object in ../../../BatchController.php on line 25 that was not appearing during testing on another linux server and a wamp server (PHP v5.2.11).

This one has stumped me. I am guessing it has something to do with the server configuration rather than the code itself. But i am just guessing. I was hoping someone here could tell me.

The only real major difference I could see, aside from the php versions and environment, is that the server that the error is on is using the Suhosin Patch. But would that be something that could cause this?

The line in question is Mage::getModel('mymodule/mymodel')->batch(); which is enclosed in an IF statement. batch() is a public function located in my model file.

If you need more code let me know.

Thanks!

Answer 1

If you get a "non-object" error when calling a model, there's a problem with Magento's attempt to get your model class, and it is returning null. The reasons for this are not always apparent. If this worked identically on a normal LAMP stack, then the problem is most likely not in your code.

My first guess would be that the file does not have the proper permissions. Otherwise, it may have to do with resolving the classname. You could test this temporarily by calling the plugin directly like this:

$obj = new Mynamespace_Mymodule_Model_Mymodel();
$obj->batch();

If this works, then the file is readable, and you will want to go spelunking in the resolution of that classname. If it doesn't work, you have a problem with either autoloading or the declaration of your class.

Hope that helps!

Thanks, Joe

Answer 2

Break it down.

You've tried to call

Mage::getModel('mymodule/mymodel')->batch();

and PHP told you it tried to call the method batch on a non-object. That means

Mage::getModel('mymodule/mymodel')

isn't returning a Model object the way it's supposed to.

First thing to do is clear out your Magento cache on the server you're having problems with. If your Module's config hasn't been loaded into the global config tree Magento will try to instantiate a Mage_Core_Model_Mymodel, and fail.

Second step is to make sure your module's app/etc/module file is in place.

Third step is to add some debugging (assuming a 1.4 branch) to the method that instantiates your objects and determine why Magento can't create your object

File:   app/code/core/Mage/Core/Model/Config.php
...
public function getModelInstance($modelClass='', $constructArguments=array())
{
    $className = $this->getModelClassName($modelClass);
    if (class_exists($className)) {
        Varien_Profiler::start('CORE::create_object_of::'.$className);
        $obj = new $className($constructArguments);
        Varien_Profiler::stop('CORE::create_object_of::'.$className);
        return $obj;
    } else {
        #throw Mage::exception('Mage_Core', Mage::helper('core')->__('Model class does not exist: %s.', $modelClass));
        return false;
    }
}
...