CodeIgniter callback functions with parameters

The problem is here:

"required|callback__Not_Selectable[$not_selectable]"

This translates to the string:

"required|callback__Not_Selectable[Array]"

This is what happens when you treat arrays as strings in PHP.

This problem is a limitation of Codeigniter's form validation library, there is no proper way to use arrays in callbacks or validation rules, you'll have to use strings. Try this:

$not_selectable = implode('|', $your_array);

This will make something like 1|4|18|33. Then set your rules as you are currently doing, but in your callback be prepared for a pipe delimited string rather than an array, and use explode() to create one:

function _Not_Selectable($option, $values_str = ''){    // Make an array        $values = explode('|', $values_str);  if(in_array($option,$values))//Is the value invalid?  {    $this->form_validation->set_message('_Not_Selectable', 'That option is not selectable.');    return false;  }  return true;}

You should extend the CI_Form_validation lib rather than trying to use callbacks.

To check if a selectbox is valid simple add default to its value then check for that.

<select><option value="default">Select one</option></select>

MY_Form_Validation

|->

public function check_select_values($option){      if($option === 'default') // try again slim jim}