Understanding config.xml: What is ?

Question

I'm new to Magento and I have a config.xml which stands for a module configuration as far as I've learned.

I have problems to understand (also to locate some sort of documentation for that, Magentos config.xml Reference is totally no-saying to me) on this very basic level already. For example the following excerpt from config.xml:

<?xml version="1.0"?>
<config>
    <modules>
        <My_Mage>
            <version>1.0.0</version>
        </My_Mage>
    </modules>
    <global>
        <models>
            <My_Mage>
                <class>My_Mage_Model</class>
            </My_Mage>
            <!-- ... --->
        </models>
    </global>
</config>

What is the part in config/globals/models about?

I guessed it was about some file on disk, however I can not find any file related to the <class> "My_Mage_Model".

For what does that part stand for?:

        <models>
            <My_Mage>
                <class>My_Mage_Model</class>
            </My_Mage>

Any hints greatly appreceated.

Looks like this is the base class name for all the models in that module. It means, that all model class names are prefixed with it (e.g. class My_Mage_Model_ConcreteModel). The module name is given within the <My_Mage> tag, corresponding to the module directory. See https://magento.stackexchange.com/questions/18269/understanding-config-xml-what-is-configglobalmodelsmy-mage - Still not sure about <globals>. — hakre, Apr 11 '14 at 14:17
means all things that are used globally, e.g. helper-, block- and model-classes, in comparison to things used only for or , e.g. observers or layout updates. If you search the web for material on how to create an own extension, many of these things will be explained. <My_Mage> is technically not only the class name, but also the module's name and the name of the directories your files are in. — simonthesorcerer, Apr 11 '14 at 19:28
@simonthesorcerer: Thanks for your comment, if you can suggest a good developer resource for modules and magento online, your sharing is highly appreceated. I have problems to find distinct resources via google, the knowledge base article I linked was a good relief, so suggestions welcome in case you know a snappy one. — hakre, Apr 14 '14 at 09:13
The correct links are: Magento for Developers: Part 1 - Introduction to Magento and Magento for Developers: Part 2 - The Magento Config - I pasted the wrong one in my first comment. — hakre, Apr 14 '14 at 09:38
Hi hakre, is this what you are searching for? http://info.magento.com/rs/magentocommerce/images/Magento-Extension-Developers-Guide-v1.0.pdf There is also the MagentoU-portal, where you can watch about 40h video material for free — simonthesorcerer, Apr 16 '14 at 18:40
@simonthesorcerer this looks very good. On Magento U I didn't found any freely accessible videos, I guess it needs some account but I don't have mine on this computer right now, so will give it a try mid next week. Thanks a lot! — hakre, Apr 17 '14 at 17:45

score 2 · Accepted Answer · answered Apr 11 '14 at 20:13

The node that contains <class>My_Mage_Model</class> registers all classes prefixed with My_Mage_Model as models that can be utilized using the Mage::getModel method. There is most likely a directory at <root>/app/code/local/My/Mage/Model/ and this is where you put any models for the "My" module.

If you were going to write a helper class for this module you would follow the same pattern - put the class in <root>/app/code/local/My/Mage/Helper/ and add a node within <global> like

<helper>
  <My_Mage>
    <class>My_Mage_Helper</class>
  </My_Mage>
 </helper>

score 2 · Answer 2 · answered Apr 12 '14 at 05:49

<global> node contains definations that should be shared between all scopes (admin, frontend, adminhtml, default)
<models> node is used for declaring models in your module.
<My_Mage> is a unique string to model declaration of your module. But mostly we are using here is Namespace_Modulename as it is also unique.
<class> node contains the path to your models folder of this particular module.

Magento will traverse in your module's model folder as app/code/codePool/My(Namespace)/Mage(Modulename)/Models

Modules's declaration is done in <modules> node.

>     <modules>
>         <My_Mage(Namespace_Modulename)> // app/code/codePool/Namespace/Modulename
>             <version>1.0.0</version>
>         </My_Mage>
>     </modules>

Understanding config.xml: What is ?

2 Answers2