code: private function appendByField($values)
  	{
  		$fixed = array();
  		
  		foreach ($this->fields as $field)
  		{
  			$fixed[] = $values[$field];
  		}
  		
  		return $this->appendByPosition($fixed);
  	}
docs: Append associative array of values.
  @param array $values Key is field name.
  @return static