Preventing double post data being resent

[eluser]worchyld[/eluser]
Typically when pressing submit on a form, and its sending POST data to itself, and you press F5, it'll bring up the message;

The page you are trying to view contains POSTDATA. If you resend the data, any action the form carried out (such as a search, or an online purchase) will be repeated.

In the past, I resolved this problem by doing this;

1. Make the form page go to a processing file (process-something.php)

2. The processing file will do whatever is needed, validation, SQL inputs, etc and then do a header redirect to step 1.

3. Pressing F5 after this does not produce the "POSTDATA" message.

How do you prevent the POSTDATA message/double posting on CI?

I thought you could do it by replicating the same procedure (ie: having a processing file act as a middleman) but the POSTDATA message still appears, also I have to repeat a lot of code over, otherwise it'll complain it's missing a page variable.

ie;

Code:

// This first controller just displays the form, it doesn't handle any processing.
// All processing is handled with a middleman to prevent double posting data being resent
// A majority of libraries, helpers, etc are assumpted to be pre-loaded
//
class Something extends Controller {

         function index() {
                $this->load->library('validation');

        // Set page variables
        $this->view->set("name", NULL);
    
        // ==================================

        // Load the actual page
        $this->view->load('something');

    } // end function

} // end controller class

Code:

// This is the view page. Its just a form, nothing more, nothing less.

<?=$this->validation->error_string; ?>
<?=$this->session->flashdata('msg');?>

<!-- BEGIN FORM -->

<?=form_open('Process_something'); ?>

<h5>Form test</h5>

<p>
<label for="name">Name:</label><br />
&lt;input type="text" name="name" id="name" value="&lt;?=$name;?&gt;" /&gt;
</p>

<p>&lt;input type="submit" value="Submit" /&gt;</p>

&lt;?=form_close();?&gt;

&lt;!-- END FORM --&gt;

Code:

// The processing middleman file
// What I've noticed is that I can't use redirect, I must use the view library in order
// to display everything I need.
// The processing middleman in this exampledoes not prevent the double posting,
// because at this point the address bar is something like
// IE: "localhost/codeignitor/index.php/process_something"
//
// Questions
// How do you prevent double posting in CI?
// I've also noticed that even if you have a middleman processing file, you have to
// recode/retype a majority of code, including page variables.
//
class Process_something extends Controller {
    
    function index()
    {    
        $this->load->library('validation');
        
        $rules['name'] = "required";

        $this->validation->set_rules($rules);

        if ($this->validation->run() == FALSE)
        {
            $this->view->set('name', null);
                
            // ==================================

            // Load the actual page
            $this->view->load('something');

        }
        else
        {            

            // Redirect to same page with success msg
            $this->session->set_flashdata('msg', 'Save succeeded');
            redirect('something');
        }
    }
}