Create a new module in magento

When you need to add new functionality or want to edit existing magento class in both case you should create a new module. Suppose, you want to add “User Credit” system then you need to create a new UserCredit module in magento. And if you want to edit/update customer functionality  then you should follow magento override rules. To override existing Customer module you should create another new customer  module name M4U_Customer in local pool. In this case you need to use magento rewrite rules. When you go to add or edit something in magento,  each time you can be done as separate module or few methods can be combined in same module if they share functionality or could be used together.

Let’s create a module :

Module Declaration:
Create app/etc/modules/M4U_NewModule.xml and write below code

<?xml version="1.0"?>
<config>
         <modules>
<!-- declare CompanyName_NewModule module -->
           <M4U_NewModule>
<!-- this is an active module -->
                  <active>true</active>
<!-- this module will be located in app/code/local code pool -->
                  <codePool>local</codePool>
<!-- specify dependencies for correct module loading order -->
                  <depends>
                             <Mage_ExistingModule />
                  </depends>
<!-- declare module's version information for database updates -->
                  <version>0.1.0</version>
           </M4U_NewModule>
	</modules>
</config>

Here is example of create new M4U_customer module to override existing Mage_Customer module and M4U_Credit module to create new credit module.

<config>
    <modules>
        <M4U_Customer>
           <active>true</active>
           <codePool>local</codePool>
        </M4U_Customer>
        <M4U_Credit>
           <active>true</active>
           <codePool>local</codePool>
        </M4U_Credit>
    </modules>
</config>

Our new module will be called NewModule.

Replace all instances of ‘NewModule’ with name of your module and ‘newmodule’ with simplified code, that contains only alphanumeric characters and underscore.

To make this tutorial most concise, it’s implied that mentioned folders will be created when needed.

Module Configuration:

Create Model, Helper, coltrollers, Block, sql and etc folder under  app/code/local/M4U/NewModule/ and configure app/code/local/M4U/NewModule/etc/config.xml like below:

<?xml version="1.0"?>
   <config>
       <modules>
           <M4U_NewModule>
                 <version>0.1.0</version>
           </M4U_NewModule>
       </modules>

<!-- define Front end controller and template  -->
       <frontend>
<!-- define Front end controller  -->
           <routers>
               <newmodule>
                   <use>standard</use>
                   <args>
                          <module>M4U_NewModule</module>
                          <frontName>newmodule</frontName>
                   </args>
               </newmodule>
           </routers>
<!-- define Front end template xml -->
           <layout>
               <updates>
                    <newmodule>
                         <file>newmodule.xml</file>
                    </newmodule>
                </updates>
              </layout>
           </frontend>   

<!-- define blocks, models, helpers in global area -->
            <global>
               <models>
                  <newmodule>
                         <class>M4U_NewModule_Model</class>
                  </newmodule>
               </models>
               <blocks>
                  <newmodule>
                          <class>M4U_NewModule_Block</class>
                  </newmodule>
               </blocks>
               <helpers>
                  <newmodule>
                          <class>M4U_NewModule_Helper</class>
                  </newmodule>
               </helpers>

<!-- declare resource setup for new module -->
               <resources>
                    <newmodule_setup>
<!-- specify that this resource is a setup resource and used for upgrades -->
                       <setup>
<!-- which module to look for install/upgrade files in -->
                           <module>M4U_NewModule</module>
                       </setup>
<!-- specify database connection for this resource -->
                       <connection>
<!-- do not create new connection, use predefined core setup connection -->
                           <use>core_setup</use>
                       </connection>
                    </newmodule_setup>
                    <newmodule_write>
                         <connection>
                              <use>core_write</use>
                         </connection>
                    </newmodule_write>
                    <newmodule_read>
                         <connection>
                               <use>core_read</use>
                         </connection>
                    </newmodule_read>
                </resources>
           </global>
      </config>

Adapter Class:
To obtain module functionality you can write necessary method in various classes as magento convention.
1. Create necessary model class in app/code/local/M4U/NewModule/Model/
2. Create Block in app/code/local/M4U/NewModule/Block/
3. Create Helper in app/code/local/M4U/NewModule/Helper/
4. Place necessary updated database sql file in app/code/local/M4U/NewModule/sql/

Frontend Template Define:

1. Define page layout in app/design/frontend/M4U/default/layout/NewModule.xml

<?xml version="1.0"?>
   <layout version="0.1.0">
     <newmodule_index_usercredit>
        <reference name="root">
            <action method="setTemplate"><template>page/1column.phtml</template></action>
        </reference>
        <update handle="customer_account"/>
        <reference name="content">
            <block type="newmodule/blockClassName" name="usercredit" template="newmodule/usercredit.phtml"/>
        </reference>
     </newmodule_index_usercredit>
</layout>

2. Create template file app/design/frontend/M4U/default/template/newmodule/usercredit.phtml

Troubleshooting

• Dont put your module in /Mage. It belongs in app/code/community/ or app/code/local/
• Make sure your module’s first letter is capitlized. newmodule apparently will not work, it must start with a capital letter Newmodule.
• If your module is not showing in configuration>advanced then check your config.xml
• Make sure you clear the cache.

In this post i described general module customization theory of Magento. For more clarification you can see next post  “write HelloWord module” in this blog.

Magento Model override rules

I worked on various e-commerce open-source such x-cart, zen-cart but Magento is the special one for his great convention and high thought system. Override system was the great thinking of Magento team. Using Magento override rules you can can easily extends any Magento feature or can add new modules. Magento follows MVC pattern. Model is one of the main pattern of MVC. Usually model is used for database connectivity and for various logical coding. Mogento also use model for same purpose. Every module of Magento have his own model class. But you can extend or modify any existing model class by following Magento override rules.

Suppose, to fulfill your project requirements you need to change or enhance customer model class. You can change code in Mage_CUstomer_Model_Customer class. But it’s not a good practice of Magento customization and when upgrade your Magento version then there have a chance of remove your customized code. Means you will lost your changes. Really it will be pathetic for you !!!!! So we should follow magento override rules. Here i tried to clear how you can easily override your various model classes.

Override Customer Model class:

At first create new module to do override work and write below code in app/etc/modules/M4U_Customer.xml

<?xml version="1.0"?>
       <config>
             <modules>
                  <M4U_Customer>
                       <active>true</active>
                       <codePool>local</codePool>
                  </M4U_Customer>
            </modules>
     </config>

Do configuration in app/code/local/M4U/Customer/etc/config.xml

<?xml version="1.0"?>
    <config>
        <modules>
            <M4U_Customer>
                <version>0.1.0</version>
            </M4U_Customer>
        </modules>

        <global>
           <models>
              <customer>
                  <rewrite>
                      <customer>M4U_Customer_Model_Customer</customer>
                 </rewrite>
              </customer>
           </models>
        </global>
  </config>

Now write your new model class M4U_Customer_Model_Cutomer and define all override method

class M4U_Customer_Model_Customer extends Mage_Customer_Model_Customer
{
   // override existing method
   public function validate()
    {
       // Define new validate rules. From now magento call this validate method instead of existing method
        //return $errors;
        return true;
    }

    // You can create new method as you needed.
    public function newMethod()
    {
       // function logic
    }
}

Override Address Model class :

Every thing is same as customer model override system. Just put a line in etc/config.xml.

<?xml version="1.0"?>
    <config>
        <modules>
            <M4U_Customer>
                <version>0.1.0</version>
            </M4U_Customer>
        </modules>

        <global>
           <models>
              <customer>
                  <rewrite>
                      <customer>M4U_Customer_Model_Customer</customer>
                      <address>M4U_Customer_Model_Address</address>
                  </rewrite>
              </customer>
           </models>
        </global>
  </config>

Now write your new model class M4U_Customer_Model_Address and define all override method

class M4U_Customer_Model_Address extends Mage_Customer_Model_Address
{
   // override existing method
   public function validate()
    {
       // Define new validate rules. From now magento call this validate method instead of existing method
        //return $errors;
        return true;
    }

    // You can create new method as you needed.
    public function newMethod()
    {
       // function logic
    }
}

Override Customer Entity Model class :

Define app/code/M4U/Customer/etc/config.xml like below. Here you will get clear concept how to override various model class in same xml.

<?xml version="1.0"?>
    <config>
        <modules>
            <M4U_Customer>
                <version>0.1.0</version>
            </M4U_Customer>
        </modules>

        <global>
           <models>
              <customer>
                  <rewrite>
                      <customer>M4U_Customer_Model_Customer</customer>
                      <address>M4U_Customer_Model_Address</address>
                  </rewrite>
              </customer>
              <customer_entity>
                  <rewrite>
                      <address>M4U_Customer_Model_Entity_Address</address>
                  </rewrite>
              </customer_entity>
           </models>
        </global>
  </config>

class M4U_Customer_Model_Entity_Address extends Mage_Customer_Model_Entity_Address
{
    protected function _afterSave(Varien_Object $address)
    {
        // Write your code
    }
}

Now just try your self. If you face any problem then make a post. I will try to help you.