Tips for Twits

Prepare the model

1. Back to the file structure drawing board

   app/
     etc/
       modules/
         - SavantDegrees_All.xml (Or what ever your company name might be)
     code/
       local/
         SavantDegrees/ (Or what ever your company name might be)
           Twit/ (Or whatever your module name might be)
             Block/
               - Index.php
             controllers/
               - AdminController.php
               - IndexController.php
             etc/
               - config.xml
             Helper/
               - Data.php
             Model/
               - Twit.php
               Mysql4/
                 - Twit.php
                 Twit/
                   - Collection.php
             sql/
               twit_setup/
                 - mysql4-install-0.2.0.php
                 - mysql4-upgrade-0.1.0-0.2.0

   Notice the new folder Model and the associated files inside. Lets clarify:
   Model/Twit.php is the logical model that holds code regarding business logic and relations.
   Model/Mysql4/Twit.php is the data implementation model that associates the model with the table and its primary key.
   Model/Mysql4/Twit/Collection.php is the data implementation model of a collection of Twit. Similar to a recordset/resultset in .Net/Java. This will be used with a Grid later.

2. Even more config.xml magic. Yay! More hairloss!

   <?xml version="1.0"?>
   <config>
       <modules>
           <SavantDegrees_Twit>
               <version>0.2.0</version>
           </SavantDegrees_Twit>
       </modules>
       <global>
           <models>
               <twit>
                   <class>SavantDegrees_Twit_Model</class>
                   <resourceModel>twit_mysql4</resourceModel>
               </twit>
               <twit_mysql4>
                   <class>SavantDegrees_Twit_Model_Mysql4</class>
                   <entities>
                       <twit>
                           <table>twit</table>
                       </twit>
                   </entities>
               </twit_mysql4>
           </models>
   	<blocks>
               <twit>
                   <class>SavantDegrees_Twit_Block</class>
               </twit>
           </blocks>
            <helpers>
               <twit><class>SavantDegrees_Twit_Helper</class></twit>
           </helpers>
           <resources>
               <twit_setup>
                   <setup>
                       <module>SavantDegrees_Twit</module>
                   </setup>
                   <connection>
                       <use>core_setup</use>
                   </connection>
               </twit_setup>
               <twit_write>
                   <connection>
                       <use>core_write</use>
                   </connection>
               </twit_write>
               <twit_read>
                   <connection>
                       <use>core_read</use>
                   </connection>
               </twit_read>
           </resources>
       </global>
       <adminhtml>
           <menu>
               <twit translate="title" module="twit">
                   <title>Twits</title>
                   <sort_order>100</sort_order>
                   <action>twit/admin</action>
               </twit>
           </menu>
       </adminhtml>
       <frontend>
           <routers>
               <SavantDegrees_Twit>
                   <use>standard</use>
                   <args>
                       <module>SavantDegrees_Twit</module>
                       <frontName>twit</frontName>
                   </args>
               </SavantDegrees_Twit>
           </routers>
       </frontend>
   </config>

   The global > models fragment define the twit table, the twit model and its resourceModel that we will be using shortly.

3. Now for the model/Twit.php code:

   <?php
   class SavantDegrees_Twit_Model_Twit extends Mage_Core_Model_Abstract
   {
    
       protected function _construct()
       {
           $this->_init('twit/twit');
       }
   }

   Whats the point you ask!? The code does nothing but binds the model to the Twit namespace under the model twit. In Java that line would have been package Twit;. *i assume/think/foretold*
   (quickly moving on…)

4. Then Model/Mysql4/Twit.php

   <?php
   class SavantDegrees_Twit_Model_Mysql4_Twit extends Mage_Core_Model_Mysql4_Abstract
   {
       protected function _construct()
       {
           $this->_init('twit/twit', 'twit_id');
       }
   }

   The code above tells Magento to hunt for the twit application’s twit table in the configuration. Yes i know the names are confusing now. Lets say instead of twit/twit it is twit/foo. In that case the system will find the configuration file associated with twit (which is our app/code/local/SavantDegrees/Twit/etc/config.xml), and look under config > global > models > twit_mysql4 > entities > foo to figure out its configuration instructions. You’ll see next that we’ll request for the table from that same configuration file. Capiche?
   As a resourceModel, the code binds the model to a underlying Mysql4 table.

5. Lastly, Model/Mysql4/Twit/Collection.php

   <?php
   class SavantDegrees_Twit_Model_Mysql4_Twit_Collection extends Varien_Data_Collection_Db
   {
       protected $_twitTable;
    
       public function __construct()
       {
           $resources = Mage::getSingleton('core/resource');
           parent::__construct($resources->getConnection('twit_read'));
           $this->_twitTable = $resources->getTableName('twit/twit');
    
           $this->_select->from(
           		array('twit'=>$this->_twitTable),
    		       	array('*')
           		);
           $this->setItemObjectClass(Mage::getConfig()->getModelClassName('twit/twit'));
       }
   }

   Basically the model files created at this phase are simply trying to tie the model (singular and collection) to the underlying Mysql resource. The entire mechanism is half tied in the config.xml table declaration, the model individual instructions (from identifying the namespace to actually declaring the primary key of the table)

6. Viola. Models are ready