public function isChanged($field = null)
    {
        if ($field) {
            $field = $this->filterInputColumn($field);
            return array_key_exists($field, $this->changedData);
        }
        return $this->isChanged;
    }
public function isChanged($field = null)
    {
        if ($field) {
            $field = $this->filterInputColumn($field);
            return array_key_exists($field, $this->changedData);
        }
        return $this->isChanged;
    }
public function isChanged ( $ field = null ) { if ( $ field ) { $ field = $ this -> filterInputColumn ( $ field ) ; return array_key_exists ( $ field , $ this -> changedData ) ; } return $ this -> isChanged ; }
Check if the record's data or specified field is changed

@param string $field
@return bool
Check if the record s data or specified field is changed