Getting a table column data as array with POST request in CakePHP - php

Question

I have a form that has a table inside it and that table has a quantity column, I want to get the quantity of all products and put them in a quantity array in the controller, is there a way I can do that? For now, it doesn't work when I click Update Cart button. Here is my current code:
index page
<section class="section service border-top">
<div>
<?= $this->Form->create(null) ?>
<fieldset>
<?php if(isset($_SESSION['cart']) && !empty($_SESSION['cart'])){?>
<table id="cart-table" class="table table-bordered table-striped">
<thead>
<tr>
<th><?= 'Products' ?></th>
<th><?= 'Price'?></th>
<th><?= 'Quantity'?></th>
<th><?= 'Sub Total'?></th>
</tr>
</thead>
<tbody>
<?php foreach ($cart_items as $cart_item): ?>
<tr>
<td><?= $cart_item->name;?></td>
<td><span id="price"><?= "$ AU".$cart_item->price;?></span></td>
<td contenteditable='true'><?php echo $this->Form->number('quantity[]',['min'=>1, 'value'=>$cart_item->quantity]); ?></td>
<td><span id="total"><?php echo "$ AU".$cart_item->price * $cart_item->quantity?></span></td>
</tr>
<?php endforeach; ?>
</tbody>
</table>
<?php }else{ ?>
You don't have any items in your cart. Add more?
<?php } ?>
</fieldset>
<?= $this->Form->button(__('Make a Payment'), ['class' => 'btn btn-success']) ?>
<?= $this->Form->button(__('Update Cart'), ['controller' => 'Carts', 'action' => 'updateCart'], ['class' => 'btn btn-success']) ?>
<?= $this->Form->end() ?>
<?= $this->Form->postLink(__('Clear Cart'), ['controller' => 'Carts', 'action' => 'clearCart'], ['class' => 'btn btn-danger', 'confirm' => __('Are you sure you want to clear your cart?')]) ?>
</section>
controller
public function updateCart()
{
if(isset($_SESSION['cart']) && !empty($_SESSION['cart'])){
if ($this->request->is('post')) {
$qty = $this->request->getData('quantity[]');
debug($this->request->getData('quantity'));
}
}
else{
$this->Flash->error(__("You don't have anything in your cart. Add more?"));
}
$this->redirect(['controller'=>'Carts','action' => 'index']);
}
Thank you