Ajax传递提示输入到php

A form is dynamically created with PHP loop and presents one row from DB. I'm asking a user for input through prompt when he changes qty, but when I send it with AJAX to PHP it's empty. I guess it's because hidden input "new_message" is filled at the same time AJAX is sending values to PHP script so at that moment is blank. For the first row generated I get a message, but not for any other row.

Can you help me how to pass prompt input to PHP script?

//Update qty on article    
$('.update_qty').on('change', function() {

  var message = prompt("Upišite razlog za izmjenu količine:");
  //e.preventDefault();

  //Get message value
  $('#new_message').val(message);

  var data = $('#form1').serializeArray();

  if (message != "" || message != NULL) {
    $.ajax({
      type: 'POST',
      url: 'update_qty.php',
      data: data,
      success: function(data) {
        alert(data);
      }
    });
  } else {
    alert("Empty");
    e.PreventDefault();
    return false;
  }
});

<tbody>
<?php if (!empty($sales_plan_list)) {
      foreach($sales_plan_list as $sales_key => $sales_value) {
 ?>
<tr class="new">
   <td>
   <a href="view_product_sales.php?id=<?php echo $sales_value['article_id']; ?>">
   <?php echo $sales_value['article_no']; ?>
   </a>
   </td>
   <td><?php echo $sales_value['description']; ?></td>
   <td><?php echo myNumberFormat($sales_value['rrp']); ?></td>
   <td>
   <form name="form1" id="form1" method="POST" action="update_qty.php">
   <input type="text" name="update_qty" class="update_qty" id="qty" value="<?php echo $sales_value['qty'] ?>"><?php echo ' Kom'; ?>
   <input type="hidden" name="article_id" id="article_id" value="<?php echo $sales_value['article_id']; ?>">
   <input type="hidden" name="sales_plan_id" id="sales_plan_id" value="<?php echo $sales_plan_id; ?>">
   <input type="hidden" name="product_mix_id" id="product_mix_id" value="<?php echo $product_mix_id; ?>">
   <input type="hidden" name="new_message" id="new_message" value="">
   </form>
   </td>
   <td>
   <a href="view_product_sales.php?id=<?php echo $sales_value['article_id']; ?>" class="ti-eye" title="Pogledaj"></a> &nbsp;&nbsp;
   <a href="edit_product_sales.php?id=<?php echo $sales_value['article_id']; ?>" class="ti-settings" title="Izmjeni"></a> &nbsp;&nbsp;
   <a href="delete_product_sales.php?id=<?php echo $sales_value['article_id']; ?>$sales_plan_id=<?php echo $sales_plan_id; ?>" class="ti-trash" title="Obriši"></a>
  </td>
   </tr>
   <?php
   }
   }
   ?>                                                                    
   </tbody>

The problem is that you have multiple elements with the same id. You should NOT do that. You check the value in jQuery and then send different form data.

This is all just quessing, I am unable to check it. But try changing id to class and make sure that you send the right form data.

For example change this

<form name="form1" id="form1" method="POST" action="update_qty.php">

to this

<form name="form1" id="form<?= $sales_key; ?>" method="POST" action="update_qty.php">