how to set unique field in my custom module

Question

I am using magento 1.9.2.4

I need to one unique and require field in my custom module form

I am using below code for form field

class Test_Brand_Block_Adminhtml_Brand_Edit_Form extends Mage_Adminhtml_Block_Widget_Form
 {
            protected function _prepareForm()
            {   
                $model = Mage::registry('test_brand');
                $fieldset->addField('option_identifier', 'text', array(
                'name'      => 'option_identifier',
                'label'     => Mage::helper('checkout')->__('Option Identifier'),
                'title'     => Mage::helper('checkout')->__('Option Identifier'),
                'required'  => true,
                ));
             }


}

Answer 1

Using 'required' => true, in form field you can make field is required. But you can not make field value unique without custom code.

You have to create database field unique and also check in your post action first if that field is unique or not if it is not unique then throw exceptation

public function postAction()
    {
        $post = $this->getRequest()->getPost();
        if ( $post ) {
            if($this->getRequest()->getPost('your-field')){
                $collection = Mage::getModel('yourmodel/yourmodel')->getCollection();
                $collection->addFieldToFilter('your-field',$this->getRequest()->getPost('your-field'));
                if(count($collection)){
                    Mage::getSingleton('customer/session')->addError(Mage::helper('yourhelper')->__('your-field name is not unique'));
                    $this->_redirect('*/*/');
                    return;
                }
            }
        }
    }

Above is example use it as reference make it as per your need

Answer 2

The best way is:

1) Add to source model this.

protected function _construct()
{
    $this->_init("your_module/your_model", "super_id");

    $this->addUniqueField(array(
        'field' => 'name',
        'title' => Mage::helper('loyalty')->__('This name has already been taken.')
    ));
}

2: Try catch exceptions of Mage_Core_Exception

try {
    $model = Mage::getModel("your_module/your_model")->load('some_id');
    $model->setName('I am bad man!');
    $model->save();

} catch (Mage_Core_Exception $e) {
    Mage::getSingleton("adminhtml/session")->addError(
    $e->getMessage()
);