我正在开发一个允许用户将模型对象添加到他们的购物车的项目，我目前正在使用 Jim McGaw 的《Beginning Django E-Commerce》一书http://www.amazon.com/exec/obidos/ASIN/1430225351/ref =nosim/liqurule-20/。我试图修改上述书中的代码以适合我的目的，但它似乎不起作用。每次我尝试添加到购物车时，我都会收到错误消息
cart_items.package_id 可能不为 NULL
我将应用程序添加到 INSTALLED_APP 元组中，我可以看到购物车甚至没有保存。只保存了 cart_id 和 date_created。
models.py (packageInfo)
from django.db import models
from django.contrib.auth.models import User
DESCRIPTION = (
('L', 'Leather Shoes'),
('E', 'Electronics'),
('F', 'Files'),
)
class PackageInfo(models.Model):
user = models.ForeignKey(User, null = True)
vendor_name = models.CharField(max_length=100)
description = models.CharField(max_length = 1, choices = DESCRIPTION)
quantity = models.IntegerField(max_length = 10)
total_value = models.IntegerField(max_length = 10)
created_at = models.DateTimeField(auto_now_add = True)
class Meta:
db_table = 'packageinfo'
ordering = ['-created_at']
def __unicode__(self):
return unicode (self.vendor_name)
models.py (Cart)
from django.db import models
from packageInfo.models import PackageInfo
class CartItem(models.Model):
cart_id = models.CharField(max_length = 50)
date_added = models.DateTimeField(auto_now_add = True)
#packageinvoice = models.ImageField(upload_to = 'invoices', help_text = '.jpg, .png, .pdf etc')
package = models.ForeignKey( PackageInfo, unique = False)
class Meta:
db_table = 'cart_items'
ordering = ['date_added']
cart.py (Cart)
from Cart.models import CartItem
from packageInfo.models import PackageInfo
from django.shortcuts import get_object_or_404
from django.http import HttpResponseRedirect
from django.contrib.auth.models import User
import random
CART_ID_SESSION_KEY = 'cart_id'
# get the current user's cart id, sets new one if blank
def _cart_id(request):
if request.session.get(CART_ID_SESSION_KEY,'') == '':
request.session[CART_ID_SESSION_KEY] = _generate_cart_id()
return request.session[CART_ID_SESSION_KEY]
def _generate_cart_id():
cart_id = ''
characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()'
cart_id_length = 50
for y in range(cart_id_length):
cart_id += characters[random.randint(0, len(characters)-1)]
return cart_id
# return all items from the current user's cart
def get_cart_items(request):
return CartItem.objects.filter(cart_id=_cart_id(request))
# add an item to the cart
def add_to_cart(request):
postdata = request.POST.copy()
vendor_name = postdata.get('vendor_name','')
description = postdata.get('description','')
quantity = postdata.get('quantity','')
total_value = postdata.get('total_value','')
ci = CartItem()
ci.vendor_name = vendor_name
ci.description = description
ci.quantity = quantity
ci.total_value = total_value
ci.cart_id = _cart_id(request)
ci.save()
forms.py (packageInfo)
from django import forms
from django.contrib.auth.models import User
from django.forms import ModelForm
from packageInfo.models import PackageInfo
class PackageInfoForm(ModelForm):
class Meta:
model = PackageInfo
# override the default __init__ so we can set the request
def __init__(self, request=None, *args, **kwargs):
self.request = request
super(PackageInfoForm, self).__init__(*args, **kwargs)
# custom validation to check for cookies
def clean(self):
if self.request:
if not self.request.session.test_cookie_worked():
raise forms.ValidationError("Cookies must be enabled.")
return self.cleaned_data
views.py (packageinfo)
from Cart import cart
from django.http import HttpResponseRedirect
from django.shortcuts import render_to_response
from django.template import RequestContext, Context
from packageInfo.forms import PackageInfoForm
def show_product(request):
if request.method == 'POST':
postdata = request.POST.copy()
form = PackageInfoForm(request, postdata)
if form.is_valid():
cart.add_to_cart(request)
if request.session.test_cookie_worked():
request.session.delete_test_cookie()
return HttpResponseRedirect('/package-information/cart/')
else:
form = PackageInfoForm(request=request)
request.session.set_test_cookie()
return render_to_response("account/package-info.html", {'form': form}, context_instance=RequestContext(request))
def show_cart(request):
cart_items = cart.get_cart_items(request)
return render_to_response("account/cart.html", {'cart_items': cart_items},
context_instance=RequestContext(request))