Using Django Sessions

[Manu Febie]

Hello,

I am practicing for my college exams. I am building a Restaurant Order System with Django and I am using Django sessions for the first. I borrowed some ideas from the "Django by example".

Below you can find the MenuItem model and Order Model.

class MenuItem(models.Model):

   category = models.ForeignKey(Category, related_name='menu_items')

   # table ???

   name = models.CharField(max_length=255, db_index=True)

   slug = models.SlugField(max_length=255, db_index=True, default='')

   description = models.TextField(blank=True)

   image = models.ImageField(upload_to='menu_items/%Y/%m/%d', blank=True)

   price = models.DecimalField(max_digits=10, decimal_places=2)

   available = models.BooleanField(default=True)

   added_on = models.DateTimeField(auto_now_add=True)

   updated = models.DateTimeField(auto_now=True)

class Order(models.Model):

STATUS_CHOICES = (

('in behandeling', 'In behandeling'),

('klaar', 'Klaar')

)

# random_id = models.CharField(max_length=255)

table = models.ForeignKey(settings.AUTH_USER_MODEL)

item = models.ForeignKey(MenuItem, related_name='order_items')

price = models.DecimalField(max_digits=10, decimal_places=2)

quantity = models.PositiveIntegerField(default=1)

status = models.CharField(max_length=50, choices=STATUS_CHOICES, default='in behandeling')

paid = models.BooleanField(default=False)

timestamp = models.DateTimeField(auto_now_add=True)

Below you can find a Cart class which handles adding, removing, iterating etc. over the Menu Items using Django sessions. What I need is a function in this class that only clears the items I have in the cart, but I still need the total price. Right now I have the "clear" function which removes the entire cart from the session. But since I am kinda confused on how to do this I need some help.

from decimal import Decimal

from django.conf import settings

from menu.models import MenuItem

class Cart:

   

   def __init__(self, request):

       self.session = request.session

       cart = self.session.get(settings.CART_SESSION_ID)

       if not cart:

           cart = self.session[settings.CART_SESSION_ID] = {}

       self.cart = cart

    def add(self, menu_item, quantity=1, update_quantity=False):

       # Add a menu item to the cart or update its quantity

       menu_item_id = str(menu_item.id)

        if menu_item_id not in self.cart:

           self.cart[menu_item_id] = {'quantity': 0,

                                      'price': str(menu_item.price)}

       

       if update_quantity:

           self.cart[menu_item_id]['quantity'] = quantity

       else:

           self.cart[menu_item_id]['quantity'] += quantity

       self.save()

    def save(self):

       # Update the session cart

       self.session[settings.CART_SESSION_ID] = self.cart

       # Mark the session as "modified" to make sure its saved

       self.session.modified = True

    def remove(self, menu_item):

       # Remove a product from the cart

       menu_item_id = str(menu_item.id)

       if menu_item_id in self.cart:

           del self.cart[menu_item_id]

           self.save()

    def __iter__(self):

       # Iterate over the item in the cart and get the products from the DB

       menu_item_ids = self.cart.keys()

       # get thte product objects and add them to the cart

       menu_items = MenuItem.objects.filter(id__in=menu_item_ids)

       

       for menu_item in menu_items:

           self.cart[str(menu_item.id)]['menu_item'] = menu_item

        for item in self.cart.values():

           item['price'] = Decimal(item['price'])

           item['total_price'] = item['price'] * item['quantity']

           yield item

    def __len__(self):

       # Count all the items in the cart

       return sum(item['quantity'] for item in self.cart.values())

    def get_total_price(self):

       return sum(Decimal(item['price']) * item['quantity'] for item in self.cart.values())

    def clear(self):

       # Remove cart from the session

       del self.session[settings.CART_SESSION_ID]

       self.session.modified = True

And below here you'll find the view that handles saving the items in the request cart in to the Order model. Instead of calling the cart.clear() function I need to call a function that removes the ordered items from the cart while still having the total price in this session.

@login_required

def create_order(request):

   cart = Cart(request)

   

   if request.method == 'POST':

       for item in cart:

           Order.objects.create(table=request.user,

                                item=item['menu_item'],

                                price=item['price'],

                                quantity=item['quantity'])

       cart.clear()

       return render(request, 'orders/order_success.html', {'cart': cart})

   

   return render(request, 'cart/cart_detail.html', {'cart': cart})

I hope my question is clear and someone can help me with this.

[Derek Zeng]

You can have a flag in cart class to mark if things are cleared. Then in the __iter__ function, check the flag before getting the keys.

If you do this you also need to add the check in add/remove and others accordingly.