Codeigniter data reinserting on page refreshing, paypal payment - php

Question

I made simple paypal payment webpage in codeigniter and when someone send payment for example, he goes to success page directly to see what he buy and if its success. When someone got redirected and press F5, the data will be inserted again in database. This here is the code I use.
Controller
if($Session) {
$paypalInfo = $this->input->post();
$data['item_number'] = $paypalInfo['item_number'];
$data['custom'] = explode('-',$paypalInfo['custom']);
$data['item_name'] = $paypalInfo['item_name'];
$data['txn_id'] = $paypalInfo["txn_id"];
$data['payment_amt'] = $paypalInfo["payment_gross"];
$data['currency_code'] = $paypalInfo["mc_currency"];
$data['status'] = $paypalInfo["payment_status"];
$IGN = $this->session->userdata['Player_Logged']['id'];
if($data['custom'][5] == 'items') {
$this->load->view('paypal/success', $data);
$datatobase['UserID'] = $IGN;
$datatobase['PackageID'] = $paypalInfo["item_number"];
$datatobase['itemid'] = $data['custom'][0];
$datatobase['txn_id'] = $paypalInfo["txn_id"];
$datatobase['payment_gross'] = $paypalInfo["mc_gross"];
$datatobase['currency_code'] = $paypalInfo["mc_currency"];
$datatobase['payer_email'] = $paypalInfo["payer_email"];
$datatobase['payment_status'] = $paypalInfo["payment_status"];
$rewardstobase['UserID'] = $IGN;
$rewardstobase['ItemID'] = $data['custom'][0];
$rewardstobase['EnhID']= "1957";
$rewardstobase['Equipped'] = "0";
$rewardstobase['Quantity'] = "1";
$rewardstobase['Bank']= "0";
$this->product->insertTransaction($datatobase);
$this->product->insertGameRewards($rewardstobase);
}
if($data['custom'][5] == 'coins') {
// Pass the transaction data to view
$this->load->view('paypal/success', $data);
// s UserCoins vzimam coins na igracha koito gi ima v databazata + dobavqm tezi ot web_storea koito kupuva
$UserCoins = $this->session->userdata['Player_Logged']['Coins'];
$coinstobase['Coins'] = $data['custom'][3] + $UserCoins;
// Insert the gamerewards data in the database
$this->product->updateCoinsRewards($coinstobase);
}
Buy Function
function buy($id){
// Set variables for paypal form
$returnURL = base_url().'paypal/success'; //payment success url
$cancelURL = base_url().'paypal/cancel'; //payment cancel url
$notifyURL = base_url().'paypal/ipn'; //ipn url
// Get product data from the database
$product = $this->product->getRows($id);
// Get current user ID from the session
//$userID = $_SESSION['userID'];
$userID = 1;
// Add fields to paypal form
$this->paypal_lib->add_field('return', $returnURL);
$this->paypal_lib->add_field('cancel_return', $cancelURL);
$this->paypal_lib->add_field('notify_url', $notifyURL);
$this->paypal_lib->add_field('item_name', $product['Title']);
//$this->paypal_lib->add_field('custom', $product['itemid']);
// tuk realno vzimam purvo itemid posle vzimam badgeid i taka natatuk moga da vzimam do bezkraq. Veche v Paypal.php, ako resha da izpolzvam primerno 'itemid' ot fiel-da 'custom', toi e raven na 0, 'BadgeID' e raven na 1 i taka vseki produkt ot 0la do zavisi kolko produkta sum dobavil, ako produktite sa 5, ot 0 do 4.
$this->paypal_lib->add_field('custom', $product['itemid'].'-'.$product['BadgeID'].'-'.$product['itemid2'].'-'.$product['Coins'].'-'.$product['Badges'].'-'.$product['ShopType']);
$this->paypal_lib->add_field('item_number', $product['id']);
//$this->paypal_lib->add_field('item_idr', $product['itemid']);
$this->paypal_lib->add_field('amount', $product['PricePayment']);
// Render paypal form
$this->paypal_lib->paypal_auto_form();
}
View Page
<div class="container">
<h2>Payment Success</h2>
<div class="row">
<div class="col-lg-12">
<h4 class="success">Thank you! Your payment was successful.</h4>
<p>Item Name : <span><?php echo $item_name; ?></span></p>
<p>Item Number : <span><?php echo $item_number; ?></span></p>
<p>TXN ID : <span><?php echo $txn_id; ?></span></p>
<p>Amount Paid : <span>$<?php echo $payment_amt.' '.$currency_code; ?></span></p>
<p>Payment Status : <span><?php echo $status; ?></span></p>
Back to Products
</div>
</div>
</div>
I tried to do it with "redirect" it works fine! But I don't want to redirect only, I want the show message so people know what buy and if its success. The expectation is if someone refresh the page - disable data reinserting or do something else for example message "Already buy" or redirect.