Delete lang when is not filled

[aXenDev]

Hi,

I'm trying change column with lang keys in DB when is not filled then column should be null, but it isn't.

It is not filled:

In database when I save node:

 

I have this code:

  /**
   * [Node] Format form values from add/edit form for save
   *
   * @param	array	$values	Values from the form
   * @return	array
   */
  public function formatFormValues($values)
  {
    if (!$values['axenserverlist_debug_text']) {
      $values["axenserverlist_debug_text"] = NULL;
    }

    return $values;
  }

but it doesn't work for me, because always return string with comma.

How can I change the code when no one has typed anything in input, then returns null in DB?