config_snippet.php

/*add me to the config file*/
'params'=>array(
		// this is used in contact page
                'date_formats' => array(  
                    'long'   => 'd/M/yyyy H:m s',
                    'medium' => 'd/M/yyyy H:m',
                    'short'  => 'd/M/yyyy')
	),

DateFormatterBehavior.php

<?php
class DateFormatterBehavior extends CActiveRecordBehavior 
{
    public $dateFields = array();
    public $allowNull = array();  // do not auto create a date for this field
    public $dateFormat = 'short';
   
    private $owner;
    
    
    public function attach($owner) 
    {
        $this->owner = $owner;
        parent::attach($owner);
    }        
            
    public function parseDate($date)
    {
        if(! empty($date) && ! is_numeric($date) )
            return parse_date($this->dateFormat, $date);
        else
            return $date;
    }
         
    public function formatDate($time)
    {
         if(! empty($time) && is_numeric($time) )
             return df($this->dateFormat, $time);
         else 
             return $time;
    }
    
    public function formatDates()
    {
        foreach($this->dateFields as $field)
            $this->owner->$field = $this->formatDate($this->owner->$field);
    }
    
    
    public function beforeSave($event)
    {
        $owner = $this->owner;
        
        foreach($this->dateFields as $field)
        {         
            //auto populate date field if empty
            if($owner->isNewRecord && !$owner->$field && !in_array($field, $this->allowNull))
                $owner->$field = time();
                
            if(is_numeric($owner->$field)) //this is for having timestamps consistent with format
            
                $owner->$field = $this->formatDate($owner->$field);
            
            
            $owner->$field = $this->parseDate($owner->$field);
        }
    }
    
    
    public function checkDate($attribute,$params = array())
    {
        $owner = $this->owner;
        
        if(empty($owner->{$attribute})) return;
            
        if(! $this->parseDate($owner->{$attribute}))
            
            $owner->addError($attribute,'The date is incorrect.');
    }
    
}

helpers.php

<?php

/* 
 * date HELPERS
 * 
 */
function df($format, $timestamp)  //date_format, user in views
{     
    return Yii::app()->dateFormatter->format(
            Yii::app()->params['date_formats'][$format],
            (int) $timestamp
           );
}


function parse_date($format, $date_string)
{
    return CDateTimeParser::parse($date_string,
                                  Yii::app()->params['date_formats'][$format]);
}

UsageExample.php

<?php

/**
 * This is the model class for table "person".
 *
 * The followings are the available columns in table 'person':
 * @property integer $id
 * @property string $name
 * @property string $surname
 * @property string $birthdate
 * @property string $address
 * @property string $city
 * @property string $telephone_n
 * @property integer $created_on
 */
class Person extends CActiveRecord
{
        /**
	 * Returns the static model of the specified AR class.
	 * @param string $className active record class name.
	 * @return Person the static model class
	 */
	public static function model($className=__CLASS__)
	{
		return parent::model($className);
	}
        
	/**
	 * @return string the associated database table name
	 */
        public function primaryKey()
	{
		return 'id';
	}
        
	public function tableName()
	{
		return 'person';
	}
        
        /*me + yii behaviours =  LOVE */
        public function behaviors() 
        { 
		return array(
                    'DateFormatterBehavior'=>array( 
                        'class'=>'ext.DateFormatterBehavior', 
			'dateFields'=>array('birthdate','last_checkin'),
                        'dateFormat' => 'short'
                    ) 
		);
	}

	/**
	 * @return array validation rules for model attributes.
	 */
	public function rules()
	{
		// NOTE: you should only define rules for those attributes that
		// will receive user inputs.
		return array(
			array('name, surname', 'required'),
			array('name, surname, birthdate, address, city, telephone_n', 'length', 'max'=>255),
			
			array('birthdate, last_checkin', 'behaviorCheckDate'),

			array('name, surname, birthdate, address, city, telephone_n', 'safe', 'on'=>'search'),
		);
	}

        //validation callback to behavior
        public function behaviorCheckDate($attribute,$params)
        {
            return  $this->checkDate($attribute,$params);  //I come from the behaviour
        }
        
        
	/**
	 * @return array relational rules.
	 */
	public function relations()
	{
		return array(
			'services' => array(self::HAS_MANY, 'Services', 'person_id'),
		);
	}
	
        
        public function beforeSave()
        {  
            return parent::beforeSave();
        }
    
    
    /**
	 * @return array customized attribute labels (name=>label)
	 */
	public function attributeLabels()
	{
		return array(
			'id' => 'ID',
			'name' => 'Name',
			'surname' => 'Surname',
			'birthdate' => 'Birth Date',
			'address' => 'Address',
			'city' => 'City',
			'telephone_n' => 'Telephone Number',
			'created_on' => 'Created On',
		);
	}

	/**
	 * Retrieves a list of models based on the current search/filter conditions.
	 * @return CActiveDataProvider the data provider that can return the models based on the search/filter conditions.
	 */
	public function search()
	{
		// Warning: Please modify the following code to remove attributes that
		// should not be searched.

		$criteria=new CDbCriteria;
               
		$criteria->compare('id',$this->id);
		$criteria->compare('name',$this->name,true);
		$criteria->compare('surname',$this->surname,true);
		$criteria->compare('birthdate',  self::parseDate($this->birthdate),true);
		$criteria->compare('address',$this->address,true);
		$criteria->compare('city',$this->city,true);
		$criteria->compare('telephone_n',$this->telephone_n,true);
                

		return new CActiveDataProvider($this, array(
			'criteria'=>$criteria,
		));
	}

}