So I'm still learning the programming side of Magento, but I thought if I copied everything that has anything to do with the Bundle product type, rename it to a new product type name (Assembly), that would get me close where I could then modify my new product type for the behavior I want. It almost worked, but obviously I'm doing something wrong. I created a new namespace under local. (MyNewNamespace) I copied every file that had anything to do with bundle into respective new files with everything changed to assembly and MyNewNamespace/Assembly for the classes.

Everything almost works, except I get Fatal error: Class 'Mage_Assembly_Helper_Data' not found.

I traced this to app/code/core/Mage/Core/Model/Config.php line 1213 in

public function getGroupedClassName($groupType, $classId, $groupRootNode=null).

On line 1253 it hardcodes mage_ to come up with the class name.

What am I missing? Can I not do what I did in my own namespace?

2 Answers 2


Looks like you need to add a Helper/Data.php file to your extension.

Check other modules to see how this is done by adding the folder/file and adding the <helper> configuration to your extension's config.xml

It does not need to have any methods, but must exist and extend the appropriate core class.

Once added and configured, Magento will stop looking for a Mage_ version.

  • I added this to my config.xml file...
    – lv2fly
    Sep 5, 2015 at 3:21
  • Forget previous statement. This one was my stupidity. Capitalized Assembly in the config.xml file. Not completely tested, but my page now loads, so its a start
    – lv2fly
    Sep 5, 2015 at 3:44

For making new product type Please go through the below link

and dowload http://inchoo.net/wp-content/uploads/2010/01/Ajzele_CustomProduct.zip

  • Thank you. I had looked at a couple things like this to create a product type from scratch, but what I want very closely mirrors a bundle, so didn't want to have to reinvent the wheel.
    – lv2fly
    Sep 5, 2015 at 3:39
  • Was actually a tossup to use bundle or group. I want to create an assembly (manufacturing term). We buy a bunch of components (which we do sell separately), but we also build items made up of components. I wanted the inventory to keep track of each item when a assembly is purchased. I didn't want each item in the assembly to be displayed like a group and didn't want the customer to be able to add/remove/change qty of the assembly items like in a bundle. Also, the isSaleable should come from if all items in assembly are in stock, but just a single fixed price. Feel free to offer a better way.
    – lv2fly
    Sep 5, 2015 at 3:43

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