我遇到了一个非常不寻常的错误，让我感到有些困惑。当我迭代购物车项目并尝试查看它们时，会抛出TypeError类型为Decimal的对象无法进行JSON序列化的错误。但是如果我从模板中删除该块，然后刷新页面，再将相同的块添加回模板并刷新页面，则可以运行。我已添加一些屏幕截图。请看一下，并帮忙解决这个问题。
cart.py
cart.py
class Cart(object):
def __init__(self, request):
"""
Initialize the cart
"""
self.session = request.session
cart = self.session.get(settings.CART_SESSION_ID)
if not cart:
# save an empty cart in the session
cart = self.session[settings.CART_SESSION_ID] = {}
self.cart = cart
def add(self, product, quantity=1, override_quantity=False):
"""
Add a product to the cart or update its quantity
"""
product_id = str(product.id)
if product_id not in self.cart:
self.cart[product_id] = {
'quantity': 0,
'price': str(product.price)
}
if override_quantity:
self.cart[product_id]['quantity'] = quantity
else:
self.cart[product_id]['quantity'] += quantity
self.save()
def __iter__(self):
"""
Iterate over the items in the cart
and get the products from the database
"""
product_ids = self.cart.keys()
# get the product objects and add the o the cart
products = Product.objects.filter(id__in=product_ids)
cart = self.cart.copy()
for product in products:
cart[str(product.id)]['product'] = product
for item in cart.values():
item['price'] = Decimal(item['price'])
item['total_price'] = item['price'] * item['quantity']
yield item
def get_total_price(self):
"""
Calculate the total cost of the items in the cart
"""
return sum(Decimal(item['price']) * item['quantity'] for item in self.cart.values())
orders.py
def order_create(request):
cart = Cart(request)
order = None
address_form = AddressCheckoutForm()
billing_address_id = request.session.get('billing_address_id', None)
shipping_address_id = request.session.get('shipping_address_id', None)
order, created = Order.objects.get_or_create(user=request.user, ordered=False)
if shipping_address_id:
shipping_address = Address.objects.get(id=shipping_address_id)
order.shipping_address = shipping_address
del request.session['shipping_address_id']
if billing_address_id:
billing_address = Address.objects.get(id=billing_address_id)
order.billing_address = billing_address
del request.session['billing_address_id']
if billing_address_id or shipping_address_id:
order.save()
if request.method == 'POST':
for item in cart:
OrderItem.objects.create(
order=order,
product=item['product'],
price=item['price'],
quantity=item['quantity']
)
order.ordered = True
order.save()
cart.clear()
return render(request, 'orders/order/created.html', {'order': order})
return render(request, 'orders/order/create.html', {'cart': cart, 'address_form': address_form, 'object': order})
create.html
<h1>Checkout</h1>
{% if not object.shipping_address %}
<h3>Shipping</h3>
{% url "addresses:checkout_address_create" as checkout_address_create %}
{% include 'address/form.html' with form=address_form next_url=request.build_absolute_uri action_url=checkout_address_create address_type='shipping' %}
{% elif not object.billing_address %}
<h3>Billing</h3>
{% url "addresses:checkout_address_create" as checkout_address_create %}
{% include 'address/form.html' with form=address_form next_url=request.build_absolute_uri action_url=checkout_address_create address_type='billing' %}
{% else %}
{% for item in cart %}
{{ item.quantity }} X {{ item.product.name }}
{{ item.total_price }}
{% endfor %}
<p>Total Price: {{ cart.get_total_price }}</p>
<form action="" method="POST">
{% csrf_token %}
<p><input type="submit" value="Place Order"></p>
</form>
{% endif %}
Traceback
Internal Server Error: /order/create/
Traceback (most recent call last):
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/core/handlers/exception.py", line 34, in inner
response = get_response(request)
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/utils/deprecation.py", line 96, in __call__
response = self.process_response(request, response)
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/contrib/sessions/middleware.py", line 58, in process_response
request.session.save()
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/contrib/sessions/backends/db.py", line 83, in save
obj = self.create_model_instance(data)
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/contrib/sessions/backends/db.py", line 70, in create_model_instance
session_data=self.encode(data),
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/contrib/sessions/backends/base.py", line 105, in encode
serialized = self.serializer().dumps(session_dict)
File "/home/duke/Monday/truck-giggle/env/lib/python3.8/site-packages/django/core/signing.py", line 87, in dumps
return json.dumps(obj, separators=(',', ':')).encode('latin-1')
File "/usr/lib/python3.8/json/__init__.py", line 234, in dumps
return cls(
File "/usr/lib/python3.8/json/encoder.py", line 199, in encode
chunks = self.iterencode(o, _one_shot=True)
File "/usr/lib/python3.8/json/encoder.py", line 257, in iterencode
return _iterencode(o, 0)
File "/usr/lib/python3.8/json/encoder.py", line 179, in default
raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type Decimal is not JSON serializable
[29/Jul/2020 14:20:17] "GET /order/create/ HTTP/1.1" 500 102125
错误
引起错误的代码块
删除该代码块
删除代码块并刷新页面后
添加代码块
添加代码块并刷新页面后
可以看到，在删除代码块之前有错误，删除代码块并刷新页面，再添加代码块回到模板并再次刷新页面后，似乎正常工作了。 你能帮我解决这个问题吗？
__iter__方法。 - Debopriyo Das