Calling a GET variable in a POST function-CodePudding

I wanted to add the $item_id into the 'bid' table after clicking on the button. But the $item_id from the $_GET cannot be passed into the $_POST function. Is it incorrect to call a variable like this?

Thank you in advance for your help!

<?php 
include ('config/dbfunctions.php'); 
include ("helpers/validateBid.php");

$user_id = "";
$item_id = "";
$table= 'bid';
$allBids = selectAll($table);
$items = selectAll('item');

if (isset($_GET['item_id'])) {
    $itemInfoPost  = selectOne('item', ['item_id' => $_GET['item_id']]);
    $item_id = $itemInfoPost['item_id'];
  } 
  

if(isset($_POST['bid-btn'])){
  
        unset($_POST['bid-btn']);
        $_POST['user_id'] = $_SESSION['user_id'];
        $_POST['item_id'] = $item_id;   //$item_id cannot be called
        $bid_id = create($table, $_POST);   
              
        header('location: itemInfo.php?item_id='."$item_id"); 
}

HTML

      <form action="itemInfo.php" method="post">
        <div >
          <h6>Place your bid</h6>
        </div>

        <div >
          <div >RM</div>
          <input   type="number" name="bid_amount">
        </div>

        <div >
          <button type="submit" name="bid-btn" >Bid Now</button>
         
        </div>
      </form>

CodePudding user response：

Please make sure that the action attribute of your form has the item id like this:

<form id="mybidform" action="itemInfo.php?item_id=123456" method="post">
    ...
</form>

or you can set the item id dynamically via JavaScript/jQuery like this before you submit your form:

$('button[name="bid-btn"]').click(function(e){
    e.preventDefault();
    let actionWithItemId = $("#mybidform").prop("action")   "?item_id="   123456;
    $("#mybidform").prop("action", actionWithItemId).submit();

});

If you don't use jQuery, I would post plain Javascript code also.