How to create IF->ELSE with input->post() with checkbox array?

Hi guys.

I have a form that has several checkbox with the same "name" attribute. I'm trying to do a conditional to know if any checkbox is checked or not, but I can not make it work. See how it is:

PHP Code:

// View (have foreach checkboxes with the name 'service[]', no other input/select/etc )
<input type = "checkbox" name = "service[]" value = "$numeric_id">

// Controller
$item = $this->input->post ('service', true);
if($item){ //Run only when submit the form
  if ($item == NULL) {
    // function if no checkbox is checked
    // return to the same page with redirect(current_url());
  }else{
   // function if at least one checkbox was marked
   // return to the same page with redirect(current_url());
  }
}else{
  //show the view with the checkboxes and submit form button
} 


The problem is that when i don't select any checkbox the input->post("service") is not NULL, not as empty or equals "" (empty).

PHP Code:

if($item==NULL) not work
if($item==FALSE) not work
if($item=='') or if($item==' ') not work
if(empty($item)) not work
if(!isset($item)) not work
if(!is_array($item)) or (is_array($item)) not work
foreach($item as $key) or foreach($item as $key => $value) not work 


Any idea what's wrong?

PHP Code:

if($item){ //Run only when submit the form
  if ($item == NULL) { 


This will never work. If you haven't selected any checkbox, $item will be empty, so the line with "if ($item == NULL) {" will not be executed.
I assume that your form has a submit button, probably with the name "submit".

PHP Code:

$submit = $this->input->post('submit');
if ($submit) {
  $items = $this->input->post('service');
  if (! empty($items)) {
    foreach($items as $item) {
        //process the checkboxes that where checked
    }
  }
  else {
      // redirect
  }

} 


PHP Code:

if($item){ //Run only when submit the form
  if ($item == NULL) { 


This will never work. If you haven't selected any checkbox, $item will be empty, so the line with "if ($item == NULL) {" will not be executed.
I assume that your form has a submit button, probably with the name "submit".

PHP Code:

$submit = $this->input->post('submit');
if ($submit) {
  $items = $this->input->post('service');
  if (! empty($items)) {
    foreach($items as $item) {
        //process the checkboxes that where checked
    }
  }
  else {
      // redirect
  }

} 


Thanks man, this work fine to me.