yii framework simple shopping cart tutorial for beginners

Provides shpping 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:

[php]
'import'=>array(
    'ext.yiiext.components.shoppingCart.*'
),

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

2 way: Registration by necessity

[php]
$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:

[php]
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.

[php]
$book = Book::model()->findByPk(1);
Yii::app()->shoppingCart->put($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.

[php]
$book = Book::model()->findByPk(1);
Yii::app()->shoppingCart->put($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.

[php]
$book = Book::model()->findByPk(1);
Yii::app()->shoppingCart->put($book,2); //1 item with id=1, quantity=2.
Yii::app()->shoppingCart->remove($book->getId()); //no items

EShoppingCart::clear()

Clears all cart items.

[php]
Yii::app()->shoppingCart->clear();

EShoppingCart::itemAt($key)

Returns item at key $key.

[php]
$position = Yii::app()->shoppingCart->itemAt(1);

EShoppingCart::contains($key)

Tells if cart contains item with id=$key.

[php]
$position = Yii::app()->shoppingCart->itemAt();

EShoppingCart::isEmpty()

Tells if cart is empty.

[php]
$position = Yii::app()->shoppingCart->isEmpty(1);

EShoppingCart::getCount()

Returns positions count.

[php]
Yii::app()->shoppingCart->put($book,2);
Yii::app()->shoppingCart->put($book2,3);
Yii::app()->shoppingCart->getCount(); //2

EShoppingCart::getItemsCount()

Returns items count.

[php]
Yii::app()->shoppingCart->put($book,2);
Yii::app()->shoppingCart->put($book2,3);
Yii::app()->shoppingCart->getItemsCount(); //5

EShoppingCart::getCost($withDiscount)

Returns cart total.

[php]
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.

[php]
$positions = Yii::app()->shoppingCart->getPositions();
foreach($positions as $position) {
...
}

IECartPosition::getPrice()

Returns a price for a single item for this position.

[php]
$positions = Yii::app()->shoppingCart->getPositions();
foreach($positions as $position) {
$price = $position->getPrice();
}

IECartPosition::getSumPrice($withDiscount)

Returns position price = single item price*items count

[php]
$book = Book::model()->findByPk(1); //price = 100
Yii::app()->shoppingCart->put($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

[php]
$book = Book::model()->findByPk(1); //price = 100
Yii::app()->shoppingCart->put($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:

[php]
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 dicount 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:

[php]
        '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:

[php]
$cN = new CallCenterNotifier();
Yii::app()->shoppingCart->attachEventHandler('onUpdatePosition',array($cN, 'updatePositionInShoppingCart'));

$book = Book::model()->findByPk(1);
Yii::app()->shoppingCart->put($book);

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.

[php]
$book = Book::model()->findByPk(1);
Yii::app()->shoppingCart[] = $book; //adding new position.

//iterating over all positions
foreach(Yii::app()->shoppingCart as $position)
{
...
}

Download yii framework simple shopping cart for beginners

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