ValueError at /cart/add_cart/1/视图carts.views.add_cart没有返回HttpResponse对象。它没有归还任何东西。http://.cart/add_cart/1/

Question

如果我将产品添加到购物车中，那么一次就可以了，然后就可以创建手推车了。但是，如果我再次添加它，则会发生上述错误。此外，在尝试编辑或删除创建的购物车时，也会出现一个错误："TypeError at /admin/carts/cartitem/3//str返回非字符串(类型为Product)“

我有Django项目，有以下模块:模型产品

from django.db import models
from category.models import Category
from django.shortcuts import reverse

class Product(models.Model):
    product_name = models.CharField(max_length=256, unique=True)
    slug = models.SlugField(max_length=256, unique=True)
    description = models.TextField(max_length=512, blank=True)
    price = models.IntegerField()
    images = models.ImageField(upload_to='photos/products') 
    stock = models.IntegerField() 
    is_available = models.BooleanField(default=True)
    category = models.ForeignKey(Category, on_delete=models.CASCADE)
    create_date = models.DateTimeField(auto_now_add=True)
    modified_date = models.DateTimeField(auto_now=True)

    def get_url(self):
        return reverse('store:product-detail', args=[self.category.slug, self.slug])
  

    def __str__(self):
        return self.product_name

模型车

from django.db import models
from store.models import Product

class Cart(models.Model):
    cart_id = models.CharField(max_length=256, blank=True)
    date_added = models.DateField(auto_now_add=True)

    def __str__(self):
        return self.cart_id


class CartItem(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    cart = models.ForeignKey(Cart, on_delete=models.CASCADE)
    quantity = models.IntegerField()
    is_active = models.BooleanField(default=True)

    def __str__(self):
        return self.product

大车视图

from django.shortcuts import render, redirect
from store.models import Product
from .models import Cart, CartItem


def _cart_id(request):
    cart = request.session.session_key
    if not cart:
        cart = request.session.create()
    return cart


def add_cart(request, product_id):
    product = Product.objects.get(id=product_id)  # get the product
    try:
        cart = Cart.objects.get(cart_id=_cart_id(request)) 
    except Cart.DoesNotExist:
        cart = Cart.objects.create(cart_id=_cart_id(request))
        cart.save()
    try:
        cart_item = CartItem.objects.get(product=product, cart=cart)
        cart_item.quantity += 1
        cart_item.save()
    except CartItem.DoesNotExist:
        cart_item = CartItem.objects.create(
            product=product,
            quantity=1,
            cart=cart,
        )
        cart_item.save()
        
        return redirect('carts:cart-view')


def cart_view(request):
    return render(request, 'store/cart.html')

手推车

from django.urls import path
from .views import cart_view, add_cart

app_name = 'carts'
urlpatterns = [
    path('', cart_view, name='cart-view'),
    path('add_cart/<int:product_id>/', add_cart, name='add-cart'),
]

和html中的标记。

{% url‘手推车:添加-购物车’single_product.id %} {% url‘小车:添加-购物车’product.id %}

Answer 1

这只是一个缩进问题。从return redirect('carts:cart-view')块中删除它并将其放入视图函数中，如下所示：

def add_cart(request, product_id):
    product = Product.objects.get(id=product_id)  # get the product
    try:
        #Logic 
    except Cart.DoesNotExist:
        #Logic
    try:
        #Logic
    except CartItem.DoesNotExist:
        #Logic
        
    return redirect('carts:cart-view')