Required Rule on specific condition - yii

Question

I need to apply rule on a form. I have a country and dependent drop down of state.
I need to apply required rule on state field.
But if i choose India from drop down then required rule should be remove from the form.
I have enabled clientsidevalidation true in cactiveform.
View form:
<?php $form = $this->beginWidget('CActiveForm', array(
'id' => 'cart',
'enableAjaxValidation' => false,
'enableClientValidation'=>true,
'clientOptions'=>array('validateOnSubmit'=>true),
// we need the next one for transmission of files in the form.
'htmlOptions' => array('enctype' => 'multipart/form-data'),
));
echo $form->dropDownList($modelUser, 'country', Countries::getcountrylistwithcode(),
array('options' => array($currentCountry=>array('selected'=>true)),
'empty'=>'Select Country',
'class'=>'form-control input-lg',
));
echo $form->error($modelUser,'country');
echo $form->labelEx($modelUser,'state',array('class'=>"col-md-30"));
echo $form->dropDownList($modelUser, 'state', $stateList,array('class'=>"form-control input-lg",'prompt'=>'Select State'));
echo $form->error($modelUser,'state');
$this->endWidget();
?>
And model rules are like this:
public function rules()
{
// NOTE: you should only define rules for those attributes that
// will receive user inputs.
return array(
array('city,country,state,address_line_one,postcode', 'required'),

Answer 1

You can achieve this by adding a custom rule to your model.
Change your rules function to something like this
public function rules()
{
// NOTE: you should only define rules for those attributes that
// will receive user inputs.
return array(
array('city,country,address_line_one,postcode', 'required'),
array('state', 'validateState'),
)
}
Next up would be to create the custom validation rule. This would look something like this
public function validateState ($attribute, $params)
{
$aCountriesWithState = array('USA');
if (in_array($this->$attribute, $aCountriesWithState) && empty($this->$attribute))
{
$this->addError($attribute, 'State is missing');
}
}