How do I get a dynamically created ID?

Question

I'm an absolute beginner in using javascript and ajax and that's why I'm stuck now. I have a while loop in which there are 2 different buttons. Both work, as I imagine, except for one little thing ...

The product-id is always passed only for the first element or, if I change it for the last element. How can I pass the correct product ID to the script?

This is my PHP file:

<?php while ( $product = $browse->fetch( PDO::FETCH_ASSOC ) ) :
    $postid = $product[ 'id' ];
    $userid = 1; ?>

 <div id="content_<?php echo $postid ?>">
 <div id="reload_<?php echo $postid ?>" class="row postfarbe browse">

  <form method='post' action="" onsubmit="return add();">
    <input type="hidden" id="userid" value="<?php echo $userid ?>" class="input-box">
    <input type="hidden" id="productid" value="<?php echo $postid ?>" class="input-box">
    <input type="hidden" id="collection" value="1" class="input-box">
    <input type="hidden" id="wish" value="0" class="input-box">
    <input type="submit" id="submit" value="Add to Collection" class="btn my-2 my-sm-0 btn-outline-dark btn-sm">
  </form>

 </div>
</div>
<?php endwhile; ?>

My Javascript is:

function add()
{
    var userid = document.getElementById("userid").value;
    var productid = document.getElementById("productid").value;
    var collection = document.getElementById("collection").value;
    var wishlist = document.getElementById("wish").value;
    if(userid && productid && collection && wishlist) {
        $.ajax
        ({
            type: 'post',
            url: 'post_collection.php',
            data: {
                user_id:userid,
                product_id:productid,
                collection_id:collection,
                wishlist_id:wishlist
            },
            success: function (response) {
                $("#content_"+ productid).load(" #reload_" + productid);
            }
        });
    }  
    return false;
}
</script>

I know that the product id in my example is always the same, but how can I pass the correct one to the script if there are 10 or more entries in the loop?

Answer 1

Your problem is that id is unique and can only be assigned once to a element, like so:

<p id="paragraph"> This is legal </p>
<p id="paragraph"> This is illegal - It is no longer unique </p>

<p class="paragraph"> This is legal </p>
<p class="paragraph"> This is legal </p>

You can access the currently clicked class by using $(this) like so:

$('.paragraph').click(function() {
    $(this).html('See, totally legal.');
});

See this example to see this in use.

---

Your solution needs to add an onclick() method to a button. This then gets the parent() form. You can then find() the class and get the val() from the form data.

Your form was also submitting the action. You need to have a <button> of type button so it does not submit the action. This must also be a class since it will not be unique if you're multiply creating them.

Here is a working example to just re-add your AJAX request too.

$(document).ready(function() {
  $('.submit-btn').click(function() {
    var elements = {
      'userid': $(this).parent().find('.userid').val(),
      'productid': $(this).parent().find('.productid').val(),
      'collection': $(this).parent().find('.collection').val(),
      'wish': $(this).parent().find('.wish').val()
    };

    console.log("User ID: " + elements.userid);
    console.log("Product ID: " + elements.productid);
    console.log("Collection: " + elements.collection);
    console.log("Wish: " + elements.wish);

    // TODO: Add your AJAX request using these elements
  });
});

button {
  background: #0084ff;
  border: none;
  border-radius: 5px;
  padding: 8px 14px;
  font-size: 15px;
  color: #fff;
  cursor: pointer;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<!-- This will be generated by PHP -->

<form method='POST'>
  <input hidden class="userid input-box" value="1">
  <input hidden class="productid input-box" value="1">
  <input hidden class="collection input-box" value="1">
  <input hidden class="wish input-box" value="1">
  <button type="button" class="submit-btn btn my-2 my-sm-0 btn-outline-dark btn-sm"> Add to collection </button>
</form>

<!-- This will be generated by PHP -->
<br />

<form method='POST'>
  <input hidden class="userid input-box" value="2">
  <input hidden class="productid input-box" value="2">
  <input hidden class="collection input-box" value="2">
  <input hidden class="wish input-box" value="2">
  <button type="button" class="submit-btn btn my-2 my-sm-0 btn-outline-dark btn-sm"> Add to collection </button>
</form>

---

Your AJAX Data will look like this:

data: {
    user_id: elements.userid,
    product_id: elements.productid,
    collection_id: elements.collection,
    wishlist_id: elements.wish
}

---

Your PHP code could look like this:

<?php foreach($browse->fetchAll(PDO::FETCH_ASSOC) as $product):
    $id = $product['id'];
    $productDd = $product['product_id'];
    $productCategory = $product['category']; // TODO: change to your column nanme
    $productWishList = $product['wish']; ?>

    <div class="content_<?= $id; ?>">
        <div class="reload_<?= $id; ?> row postfarbe browse">
            <form method='POST'>
                <input hidden class="userid input-box" value="<?= $id; ?>">
                <input hidden class="productid input-box" value="<?= $productCategory; ?>">
                <input hidden class="collection input-box" value="<?= $productCollection; ?>">
                <input hidden class="wish input-box" value="<?= $productWishList; ?>">
                <button type="button" class="submit-btn btn my-2 my-sm-0 btn-outline-dark btn-sm"> Add to collection </button>
            </form>
        </div>
    </div>

<?php endforeach; ?>

Answer 2

I read your code , You want to have multiple entries and want to read / fetch dynamically generated Form's Feilds in the common JS Function Add which is currently referring to FIRST FOUND ELEMENT IN RENDERED HTML - Thats the reason you are getting the same value each time.

You need to alter the logic with little tric - Pass something uniqueness in argument of ADD function

<form method='post' action="" onsubmit="return add(<?php echo $postid; ?> );">
<input type="hidden" id="<?php echo $postid; ?>_userid" value="<?php echo $userid ?>" class="input-box">
<input type="hidden" id="<?php echo $postid; ?>_productid" value="<?php echo $postid ?>" class="input-box">
<input type="hidden" id="<?php echo $postid; ?>_collection" value="1" class="input-box">
<input type="hidden" id="<?php echo $postid; ?>_wish" value="0" class="input-box">
<input type="submit" id="<?php echo $postid; ?>_submit" value="Add to Collection" class="btn my-2 my-sm-0 btn-outline-dark btn-sm">

NOW read uniquely in ADD Function

function add(post_id){

var userid = document.getElementById(post_id+"_userid").value;
var productid = document.getElementById(post_id+"_productid").value;
var collection = document.getElementById(post_id+"_collection").value;
var wishlist = document.getElementById(post_id+"_wish").value;
### Your code as it is ...  
}

Hope this make you sense How i have generated in Loop Unique ELEMENT ID and pass same ID in the function as Argument to fetch them in JS.