public function getDateValidationRule()
    {
        if ($this->isDateOrTime()) {
            if (!empty($this->dateFormat)) {
                return sprintf('date_format:%s', $this->dateFormat);
            }

            return 'date';
        }

        return null;
    }
public function getDateValidationRule()
    {
        if ($this->isDateOrTime()) {
            if (!empty($this->dateFormat)) {
                return sprintf('date_format:%s', $this->dateFormat);
            }

            return 'date';
        }

        return null;
    }
public function getDateValidationRule ( ) { if ( $ this -> isDateOrTime ( ) ) { if ( ! empty ( $ this -> dateFormat ) ) { return sprintf ( 'date_format:%s' , $ this -> dateFormat ) ; } return 'date' ; } return null ; }
Gets date validation rule for a datetime field.

@return mix (null | string)
Gets date validation rule for a datetime field .