duplicate data insert in CodeIgniter

Question

I am just inserting data in codeigniter controller part at pastebin http://pastebin.com/KBtqrAkZ

  public function add_product()
  {
    $this->lang->load('log_in', 'english');
        log_in_check($this->lang->line('log_in_authentication_error'), 'admin/log_in');
        $this->lang->load('common', 'english');
        $data['title'] = $this->lang->line('admin_index_title');
        $this->load->view('admin_template/header', $data);
        $this->load->view('admin_template/left_menu');
    $data['error_msg'] = '';
        if ($this->form_validation->run('add_product') === TRUE)
        {
      $this->admin_model->add_product($this->input->post());
            $this->session->set_flashdata('status_msg', $this->lang->line('add_product_success'));
            redirect(uri_string(), 'refresh');
      exit ;
          $data['error_msg'] = $this->lang->line('add_product_invalid_data');
        }
        $this->load->view('admin/add_product');
        //$this->load->view('admin_template/notification');
        $this->load->view('admin_template/footer');  
  }

Than my model part is simple add at pastebin http://pastebin.com/WiLHV2sr

  public function add_product($data = array())
  {
    $this->db->insert('ishop_product', $data);
    return $this->db->insert_id();
  }

my problem is after redirecting if I press ctrl + F5 or F5 than the data is inserting. I am a new in codeigniter. Help me please. Any help will be greatly appreciated.

Answer 1

This is the Double Submit Problem.

There are several ways of dealing with it:

1. The Post / Redirect / Get pattern: Breaks the back button, and it does not keep your user from going back far enough to submit again. Does not handle multiple clicks.

2. Disable the submit button: Handles multiple clicks some of the time, but does not fix the user going back and submitting again.

3. Store a token in the session: If you have multiple tabs open in the browser, the token stored in the session may get mixed up. (Note: It may be possible to create browser tab specific cookies using javascript, but I have not tried it myself.)

4. Change the database to not allow duplicates: The best solution, but also the most effort. If it detects a set of duplicate data, ignore the second request.

5. Unique transaction id: Described on this PHP hacks page, and on this answer.

6. Multiple tokens in the session: A variation on option 3. If you store all generated tokens in the session, you don't need to involve the database. The probability of a duplicate is much lower, given that tokens are unique inside a session. Possible problems include the set of tokens growing out of control. Maybe fixable with a limited size stack where you add to the top of the stack, and extra tokens fall off the bottom. Untested.

--

I like the unique transaction id method. It works like this:

1. Generate a random transaction_id and put it in your web form. It goes along when the user clicks submit.

2. When you receive the request to add a product, check for the transaction_id in the transaction table.

3. If the id does not exist in the table, do the transaction, and insert the transaction_id into the table.

4. If the id does exist in the table, the transaction is already done.

You should also search for [double-submit-prevention] in to see if you can find an even better solution.