Setup Script – Mage_Core_Model_Resource_Setup vs Mage_Eav_Model_Entity_Setup

I managed to add a field to the registration page and have it saved to the database. thanks to the help of this tutorial. I have added my code which has done the job.

Sorry there is no explanation to the code or an answer to what is customer_account_edit and customer_account_create and how is setData() parameter decided. But I thought this code may be helpful for anyone else adding new fields. Hopefully someone with more knowledge will expand on that part

config.xml

<global>
    <fieldsets>
        <customer_account>
            <username>
                <create>1</create>
                <update>1</update>
                <name>1</name>
            </username>
        </customer_account>
    </fieldsets>

    <resources>
        <customforms_reginfo_setup>
            <setup>
                <module>Customforms_Reginfo</module>
                <class>Mage_Customer_Model_Entity_Setup</class>
            </setup>
            <connection>
                <use>core_setup</use>
            </connection>
        </customforms_reginfo_setup>
    </resources>
</global>

setup-0.1.0.php

 $installer = $this;

 $installer->startSetup();

 $this->addAttribute('customer', 'username', array(
'type' => 'varchar',
'input' => 'text',
'label' => 'Username',
'global' => 1,
'visible' => 1,
'required' => 1,
'user_defined' => 1,
'visible_on_front' => 1
 ));

Mage::getSingleton('eav/config')
->getAttribute('customer', 'username')
->setData('used_in_forms', array('adminhtml_customer', 'customer_account_edit','customer_account_create'))
->save();
$installer->endSetup();

Try it like this:

->addForeignKey(
     $installer->getFkName('namespace_module/shop', 'area_id', 'namespace_module/area','area_id'),
     'area_id',
     $installer->getTable('namespace_module/area'), 
     'area_id',
     Varien_Db_Ddl_Table::ACTION_CASCADE, 
     Varien_Db_Ddl_Table::ACTION_CASCADE
)  

The difference in my code is that I removed the first line below getFkName.
since you are calling addForeignKey on a table while creating it, you don't need to specify it's name again.

as a general rule use:

->addForeignKey(
     $installer->getFkName('TABLE ALIAS', 'FK_FIELD', 'REF_TABLE_ALIAS','REF_TABLE_FIELD'),
     'CURRENT_TABLE_FIELD_NAME',
     $installer->getTable('REF_TABLE_ALIAS'), 
     'REF_TABLE_FIELD',
     Varien_Db_Ddl_Table::ACTION_CASCADE, 
     Varien_Db_Ddl_Table::ACTION_CASCADE
)  

[Edit]
You should be looking at Varien_Db_Ddl_Table::addForeignKey because you are using it on an instance of Varien_Db_Ddl_Table.