用django做购物车，为什么购物车中相同的物品不能合并成一个？

Question

是根据这一个教程做的
http://www.cnblogs.com/holbrook/archive/2012/03/02/2357343.html

view_cart.html

{% extends "base.html" %} {% block title %} 我的购物车{% endblock %} {% block pagename %} 我的购物车 {% endblock %} {% block content %}
<div class="row">
  <div class="span10">
    <table class="condensed-table">
      <thead>
        <tr>
          <th class="header">数量</th>
          <th class="yellow header">名称</th>
          <th class="blue header">单价</th>
          <th class="green header">小计</th>
        </tr>
      </thead>
      <tbody>
        {% for item in cart.items %}
        <tr>
          <th>{{item.quantity}}</th>
          <td>{{item.product.title}}</td>
          <td>{{item.unit_price}}</td>
          <td>{% widthratio item.quantity 1 item.unit_price %}</td>
        </tr>
        {% endfor %}
        <tr>
          <th></th>
          <td></td>
          <th>总计：</th>
          <th>{{cart.total_price}}</th>
          <th>数量：</th>
          <th>{% for item in cart.items %}{{item.quantity}}{% endfor %}</th>
        </tr>
      </tbody>
    </table>
  </div>
  <div class="span4">
    <p><a class="btn primary span2" href="#">继续购物</a></a>
    </p>
    <p><a class="btn danger span2" href="{% url 'depotapp:clean_cart'%}">清空购物车</a>
    </p>
    <p><a class="btn success span2" href="#">结算</a>
    </p>
  </div>
</div>
{% endblock %}

views.py :

def view_cart(request):
    cart = request.session.get("cart",None)
    t = get_template('depotapp/view_cart.html')
    if not cart:
        cart = Cart()
        request.session["cart"] = cart
    c = RequestContext(request,locals())
    return HttpResponse(t.render(c))

models.py

class Cart(object):
    def __init__(self, *args, **kwargs):
        self.items = []
        self.total_price = 0
    def add_product(self,product):
        self.total_price += product.price
        for item in self.items:
            if item.product.id == product.id:
                item.quantity += 1
        return self.items.append(LineItem(product=product,unit_price=product.price,quantity=1))    

Answer 1

你的 add_product 错了，return 的位置不对

        def add_product(self,product):
            self.total_price += product.price
            for item in self.items:
                if item.product.id == product.id:
                    item.quantity += 1
                    return
            self.items.append(LineItem(product=product,unit_price=product.price,quantity=1)) 

Answer 2

请问一下，你现在还有这个教程的源代码吗？我现在也在根据这个教材做，可是也遇到了好多问题