How to access form element in while loop in PHP - php

Question

i want to get acces to comment and get the value of it , i used $_POST but i get error
Undefined array key
the code create photo posts with while loop the post also contains the comment section.
here the Photo post code:
<!-- Photos section -->
<section>
<div class="container mt-5">
<div class="album py-5 bg-light">
<div class="row row-cols-1 row-cols-sm-1 row-cols-md-1 row-cols-lg-1">
<div class="container">
<?php
if (mysqli_num_rows($res_for_pics) > 0) {
while ($pics = mysqli_fetch_assoc($res_for_pics)) { ?>
<div class="col mb-3">
<div class="card shadow-sm">
<img src="images/user/<?= $pics['pic'] ?>" class="card-img-top img-fluid" alt="...">
<div class="card-body">
<h5 class="card-title" id="add-com"><?php echo $pics['pic_title'] ?></h5>
<p class="card-text"><?php echo $pics['pic_des'] ?></p>
<div class="d-flex justify-content-between align-items-center">
<small class="text-muted mb-3">by nithan</small>
</div>
<div class="accordion-item">
<h2 class="accordion-header" id="headingOne">
<button class="accordion-button" type="button" data-bs-toggle="collapse" data-bs-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne">
<h5 class="card-title"> Comments</h5>
</button>
</h2>
<div id="collapseOne" class="accordion-collapse collapse show" aria-labelledby="headingOne" data-bs-parent="#accordionExample">
<div class="accordion-body">
<ul class="list-group list-group-flush">
<li class="list-group-item">
howa
<p class="card-text"><small class="text-muted"></small></p>
</li>
</ul>
</div>
</div>
</div>
**I Want to get access to the value of textarea in the other php file**.
<form method="$_POST" action="../model/comment.php">
<div class="mb-3 mt-5">
<h5 for="message-text" class="col-form-label">add your comment</h5>
<textarea type="text" class="form-control" id="message-text" name="theComment"></textarea>
</div>
<button type="submit" class="btn btn-primary text-light" name="addComment">Comment</button>
</form>
</div>
</div>
</div>
<?php }
} ?>
</div>
</div>
</div>
</div>
</section>
and here comment.php
<?php
include('db_con.php');
$comment = $_POST["theComment"];
echo $comment;
So i try to get access to the 'theComment' value from the form .