Yii Framework Simple Shopping Cart Tutorial for Beginners

Provides shopping cart functionality for models. Cart is a container object that holds items collection and have handy methods to work with it. It uses user session as a cart data storage. 

INSTALLING AND CONFIGURING

1 way: Registration in the config file

Add to protected/config/main.php: 

'import'=>array(     'ext.yiiext.components.shoppingCart.*' ),   'components' => array(   'shoppingCart' =>     array(         'class' => 'ext.yiiext.components.shoppingCart.EShoppingCart',     ),   )

2 way: Registration by necessity

$cart = Yii::createComponent(array(     'class' => 'ext.yiiext.components.shoppingCart.EShoppingCart' )); //Important! $cart->init();   $book = Book::model()->findByPk(1);   $cart->put($book);

PREPARING A MODEL

Models that you are planning to put into the cart should implement IECartPosition interface: 

class Book extends CActiveRecord implements IECartPosition {     public static function model($className = __CLASS__) {         return parent::model($className);     }       function getId(){         return 'Book'.$this->id;     }       function getPrice(){         return $this->price;     } }

API

EShoppingCart::put($position, $quantity)

Adds $quantity items to the cart. If item is already in the cart, item data is being updated and item quantity is summed with $quantity. 

$book = Book::model()->findByPk(1); Yii::app()->shoppingCart->put($book); //1 item with id=1, quantity=1. Yii::app()->shoppingCart->put($book,2); //1 item with id=1, quantity=3. $book2 = Book::model()->findByPk(2); Yii::app()->shoppingCart->put($book2); //2 items with id=1 and id=2. EShoppingCart::update($position, $quantity)

Updates cart item. If item is already in the cart, item data is being updated and item quantity is set to $quantity. If there is no such item yet it will be added. If $quantity<1 then item will be deleted. 

$book = Book::model()->findByPk(1); Yii::app()->shoppingCart->put($book); //1 item with id=1, quantity=1. Yii::app()->shoppingCart->update($book,2); //1 item with id=1, quantity=2. EShoppingCart::remove($key)

Removes item from the cart. 

$book = Book::model()->findByPk(1); Yii::app()->shoppingCart->put($book,2); //1 item with id=1, quantity=2. Yii::app()->shoppingCart->remove($book->getId()); //no items EShoppingCart::clear() Clears all cart items.

Clears all cart items. 

Yii::app()->shoppingCart->clear(); EShoppingCart::itemAt($key)

Returns item at key $key. 

$position = Yii::app()->shoppingCart->itemAt(1); EShoppingCart::contains($key)

Tells if cart contains item with id=$key. 

$position = Yii::app()->shoppingCart->itemAt(); EShoppingCart::isEmpty()

Tells if cart is empty. 

$position = Yii::app()->shoppingCart->isEmpty(1); EShoppingCart::getCount()

Returns positions count. 

Yii::app()->shoppingCart->put($book,2); Yii::app()->shoppingCart->put($book2,3); Yii::app()->shoppingCart->getCount(); //2 EShoppingCart::getItemsCount()

Returns items count. 

Yii::app()->shoppingCart->put($book,2); Yii::app()->shoppingCart->put($book2,3); Yii::app()->shoppingCart->getItemsCount(); //5 EShoppingCart::getCost($withDiscount)

Returns cart total. 

Yii::app()->shoppingCart->put($book,2); //price=100 Yii::app()->shoppingCart->put($book2,1); //price=200 Yii::app()->shoppingCart->getCost(); //400 EShoppingCart::getPositions()

Returns an array with all positions. 

$positions = Yii::app()->shoppingCart->getPositions(); foreach($positions as $position) { ... } IECartPosition::getPrice()

Returns a price for a single item for this position. 

$positions = Yii::app()->shoppingCart->getPositions(); foreach($positions as $position) {     $price = $position->getPrice(); } IECartPosition::getSumPrice($withDiscount)

Returns position price = single item price*items count 

$book = Book::model()->findByPk(1); //price = 100 Yii::app()->shoppingCart->put($book,2); //putting 2 items $positions = Yii::app()->shoppingCart->getPositions(); foreach($positions as $position) {     $price = $position->getSumPrice(); //200 (2*100) } IECartPosition::getQuantity()

Returns position items quantity 

$book = Book::model()->findByPk(1); //price = 100 Yii::app()->shoppingCart->put($book,2); //putting 2 items $positions = Yii::app()->shoppingCart->getPositions(); foreach($positions as $position) {     $price = $position->getQuantity(); //2 }

DISCOUNTS

There is a single discount system built in. It allows to apply a set of rules that will change cart total or a single position price. Discount is a class that implements IEDiscount and defines apply() method that describes how exactly discount is applied. Discount is calculated by applying Position::addDiscountPrice/Position::setDiscountPrice position's method or EShoppingCart::addDiscountPrice/EShoppingCart::setDiscountPrice cart-wide method. This methods are getting one parameter that holds a value of cart total reduction or individual position reduction. Discount class example: 

class TestDiscount extends IEDiscount {     /**      * % discount      */     public $rate = 30;       public function apply() {         foreach ($this->shoppingCart as $position) {             $quantity = $position->getQuantity();             if ($quantity > 1) {                 $discountPrice = $this->rate * $position->getPrice() / 100;                 $position->addDiscountPrice($discountPrice);             }         }     }   }

This example discount works like this: if there is more than one item for a single position, there will be $rate % discount for one item and it will be applied to position price. You can apply unlimited discount rules that will be called one by one: 

'shoppingCart' =>     array(         'class' => 'ext.yiiext.components.shoppingCart.EShoppingCart',         'discounts' =>         array(             array(                 'class' => 'ext.yiiext.components.shoppingCart.discounts.TestDiscount',                 'rate' => 40),             array('class' => 'otherDiscount'),         ),       ),

EVENTS

There are 2 events in ShoppingCart implemented in a standard Yii way: 

1. onUpdatePosition - is triggered when position is added or updated. 
2. onRemovePosition - is triggered when position is deleted.

Usage: 

$book = Book::model()->findByPk(1); Yii::app()->shoppingCart[] = $book; //adding new position.   //iterating over all positions foreach(Yii::app()->shoppingCart as $position) { ...   }

When onUpdatePosition event is fired, call center will be notified. 

WORKING WITH A CART AS CMAP

ShoppingCart is a child of CMap so you can work with the cart as an array.