cakephp 3.4 shopping cart - cakephp-3.0

Question

I am using cakephp 3.4 for my project. I am trying to add shoping cart. I got an example of shopping cart for cakephp 2 from the following link:
https://www.startutorial.com/articles/view/build-a-shopping-cart-with-cakephp-and-jquery-part-2
I was trying to add it to my project. I couldn't able to add more than one data to the cart.
Also, when I click the update button from 'shopping cart view', it shows the following error:
Error: Call to a member function saveProduct() on boolean
File my_project_url\src\Controller\CartsController.php
Line: 59
Here is my code:
Product view
<div class="single-but item_add">
<?php echo $this->Form->create('Cart', ['id'=>'add-form', 'url' => ['controller'=>'carts', 'action' => 'add']]); ?>
<?php echo $this->Form->hidden('product_id',array('value'=>$fruit->id))?>
<input type="submit" value="add to cart"/>
<?= $this->Form->end() ?>
Shopping cart view
<?php echo $this->Form->create('Cart',array('url'=>array('controller'=>'carts', 'action'=>'update')));?>
<div class="row">
<div class="col-lg-12">
<table class="table">
<thead>
<tr>
<th>Product Name</th>
<th>Price</th>
<th>Quantity</th>
<th>Total</th>
</tr>
</thead>
<tbody>
<?php $total=0;?>
<?php foreach ($products as $product):?>
<tr>
<td><?php echo $product['name'];?></td>
<td>tk. <?php echo $product['price_exact'];?>
</td>
<td><div class="col-xs-3">
<?php echo $this->Form->hidden('product_id.',array('value'=>$product['Product']['id']));?>
<?php echo $this->Form->input('count.',array('type'=>'number', 'label'=>false,
'class'=>'form-control input-sm', 'value'=>$product['count']));?>
</div></td>
<td>tk. <?php echo $product['count']*$product['price_exact']; ?>
</td>
</tr>
<?php $total = $total + ($product['count']*$product['price_exact']);?>
<?php endforeach;?>
<tr class="success">
<td colspan=3></td>
<td>tk. <?php echo $total;?>
</td>
</tr>
</tbody>
</table>
<p class="text-right">
<?php echo $this->Form->submit('Update',array('class'=>'btn btn-warning','div'=>false));?>
<a class="btn btn-success"
onclick="alert('Implement a payment module for buyer to make a payment.');">CheckOut</a>
</p>
</div>
</div>
<?php echo $this->Form->end();?>
CartsController.php
<?php
namespace App\Controller;
use App\Controller\AppController;
use Cake\Event\Event;
use Cake\Core\Configure;
class CartsController extends AppController {
public function beforeFilter(Event $event)
{
// allow all action
$this->Auth->allow();
}
public function add() {
$this->autoRender = false;
if ($this->request->is('post')) {
$this->Carts->addProduct($this->request->data['product_id']);
}
echo $this->Carts->getCount();
$this->redirect(['controller'=>'fruits', 'action' => 'index']);
}
public function view() {
$this->loadModel('Fruits');
$carts = $this->Carts->readProduct();
$products = array();
if (null!=$carts) {
foreach ($carts as $productId => $count) {
$product = $this->Fruits->get($productId);
$product['count'] = $count;
$products[]=$product;
}
}
$this->set(compact('products'));
}
public function update() {
if ($this->request->is('post')) {
if (!empty($this->request->data)) {
$cart = array();
foreach ($this->request->data['count'] as $index=>$count) {
if ($count>0) {
$productId = $this->request->data['id'][$index];
$cart[$productId] = $count;
}
}
$this->Cart->saveProduct($cart);
}
}
$this->redirect(array('action'=>'view'));
}
}
CartsTable.php
<?php
namespace App\Model\Table;
use Cake\ORM\Query;
use Cake\ORM\RulesChecker;
use Cake\ORM\Table;
use Cake\Validation\Validator;
use Cake\ORM\TableRegistry;
use Cake\Network\Session;
use Cake\Core\Configure;
class CartsTable extends Table
{
/**
* Initialize method
*
* #param array $config The configuration for the Table.
* #return void
*/
public function initialize(array $config)
{
parent::initialize($config);
$this->setTable('carts');
}
/*
* add a product to cart
*/
public function addProduct($productId) {
$allProducts = $this->readProduct();
if (null!=$allProducts) {
if (array_key_exists($productId, $allProducts)) {
$allProducts[$productId]++;
} else {
$allProducts[$productId] = 1;
}
} else {
$allProducts[$productId] = 1;
$this->saveProduct($allProducts);
}
}
/*
* get total count of products
*/
public function getCount() {
$allProducts = $this->readProduct();
if (count($allProducts)<1) {
return 0;
}
$count = 0;
foreach ($allProducts as $product) {
$count=$count+$product;
}
return $count;
}
/*
* save data to session
*/
public function saveProduct($data) {
$session = new Session();
return $session->write('cart',$data);
}
/*
* read cart data from session
*/
public function readProduct() {
$session = new Session();
return $session->read('cart');
}
}

Answer 1

In CakePHP 3 you must call a method from the Table class witch is in plural form, so in this part of your controller:
$this->Cart->saveProduct($cart);
you must use:
$this->Carts->saveProduct($cart);