How to make CodeIgniter callable work for checkboxes that are left empty, custom form validation bug

You can create your rules in a form_validation file inside /config

application/config/form_validation.php

$config = array(    'controller/method' => array(        array('field'=>'', 'label'=>'', 'rules'=>'required|acceptTerms')        array('field'=>'another', 'label'=>'', 'rules'=>'required')    ),);

Note the controller/method for the key, Codeigniter will use this if you don't set it specifically inside the calling form_validation function.

An example of this would be like so

application/controllers/Shop

class Shop extends CI_Controller{    public function __construct(){ parent::__construct(); }    public function index()    {        // Show the Purchase Form        // in some view        return $this->load->view();    }    public function purchase()    {        // notice we don't pass any params to the run() function        // codeigniter will look inside application/config/form_validation/$config        // for any matching key, ie: shop/purchase        if(!$this->form_validation->run()){             // If validation fails, show the form again            // and stop the method from executing any further            return $this->index();        }    }}

To validate if check boxes are set, we look for the keyword on

application/libraries/MY_Form_validation.php

class MY_Form_validation extends CI_Form_validation{    public function __construct($config)    {        parent::__construct( $config );    }    public function acceptTerms( $field )    {        $this->set_error('acceptTerms', 'your error message');        return (bool) $field == 'on';    }}

$terms = $this->input->post('terms');var_dump((int)$checked); //Just to see the value, then remove this line.if((int)$checked == 1) {  //Checked = True} else {  //Checked = False}

I'll check about the required flag and edit this answer.

Edit:Instead of just required, try to use required|isset, then when you perform callback_terms_accepted, do something like this:

function terms_accepted($value) {  if (isset($checked)) {    return true;  } else {    $this->form_validation->set_message('terms_accepted', 'Error message');    return false;  }}

That should do the trick.

Again, hope that helps mate.

Alright, I managed to fix my problem. The issue here was as I suspected a bug in CodeIgniter related to callables specifically.

NOTE: This bug seems to have been fixed in CI 3.0.1+. I was running version 3.0.0.

The problem

The problem is that the Form_validation library has a piece of code in the _execute function that checks if there is either a required rule or a callback rule set for a field that isn't posted. This applies to checkboxes since they aren't part of the $_POST array when left empty. This is the code that causes the issue:

$callback = FALSE;if ( ! in_array('required', $rules) && ($postdata === NULL OR $postdata === '')){    // Before we bail out, does the rule contain a callback?    foreach ($rules as &$rule)    {        if (is_string($rule))        {            if (strncmp($rule, 'callback_', 9) === 0)            {                $callback = TRUE;                $rules = array(1 => $rule);                break;            }        }        elseif (is_callable($rule))        {            $callback = TRUE;            $rules = array(1 => $rule);            break;        }    }    if ( ! $callback)    {        return;    }}

This code is used to skip validation entirely for a field if it is not required or has a callback. However, the CI devs made the mistake of checking for callbacks with is_callable. This of course is fine for normal callables that are structured like this:

array($this->some_model_or_library, 'function_name')

But, CodeIgniter allows you to name your callback in order to set validation errors for it like this:

array('my_callback_function', array($this->some_model_or_library, 'function_name'))

Unsurprisingly, is_callable returns false when applied to this array, and thus validation is skipped.

Relevant docs: http://www.codeigniter.com/user_guide/libraries/form_validation.html#callable-use-anything-as-a-rule

The solution

Personally, I didn't see the use of the abovementioned code, because I never want to skip validation when a field isn't posted. So I solved the problem by creating a MY_Form_validation class and overriding the _execute function, simply replacing the code with:

$callback = TRUE;

Of course, a slightly more conservative solution would be to check for multidimensional arrays and apply is_callable to the appropriate element like so:

if (is_callable($rule)                            // Original check.|| (is_array($callback) && is_array($callback[1]) // Check if the callback is an array and contains an array as second element.&& is_callable($callback[1]))                     // Check if the second element is a callable.