Python/Django:RelatedObjectDoesNotExist:Cart没有用户

我的数据库中有3个表.User,Flower和Cart.我正在尝试为用户登录的用户创建购物车体验,获取购物车,可以将商品添加到购物车,然后从购物车中订购商品.

我Cart有一个ManyToManyField(Flower)和我User有一个OneToOneField(Cart).当用户向他们的购物车添加内容时,我需要为他们创建购物车,然后存储他们的用户ID以及他们点击添加到购物车的花ID(或名称).

目前这是我要经历的顺序......

1)通过数据库抓取用户 p1 = User.objects.filter(username = 'erik')

2)从列表中抓取用户对象 p1 = [0]

3) c1 = Cart(id = 1)

4) c1.user.add(p1)

我收到以下错误: RelatedObjectDoesNotExist: Cart has no user.

为什么这不起作用,我怎样才能让它做我需要它做的事情？

我的模特......

from __future__ import unicode_literals
from django.contrib.auth.models import User
from django.db import models

class Flower(models.Model):
    name = models.CharField(max_length=255)
    link = models.CharField(max_length=255)
    created_at = models.DateField(auto_now_add=True)

    def __str__(self):
        return self.name
class Meta:
    db_table = 'Flower'

class Cart(models.Model): 
    userid = models.CharField(max_length=255)
    flowername = models.CharField(max_length=255) 
    user = models.OneToOneField(User)
    flower = models.ManyToManyField(Flower)

Aakash Rayat.. 5

我认为在这种情况下使用的正确架构如下:

class Cart(models.Model):
    user = models.OneToOneField(User, related_name='cart')        
    date_added = models.DateTimeField(auto_now_add=True, help_text="Date when cart is added.")
    date_modified = models.DateTimeField(auto_now=True, help_text="Date when cart is modified.")


class CartDetail(models.Model):
    cart = models.ForeignKey(Cart, related_name='cart_details')
    flower = models.ForeignKey(Flower)
    quantity = models.PositiveSmallIntegerField(help_text='Quantity to be purchased.')
    date_added = models.DateTimeField(auto_now_add=True,
                                      help_text="Date when this item is added.")
    date_modified = models.DateTimeField(auto_now=True, help_text="Date when this item is modified.")

因此,在这种情况下,您可以通过以下方式获取用户的购物车详情:

try:
    cart = request.user.cart
except Cart.DoesNotExist:
    cart = Cart.objects.create(user=request.user)
    cart_details = cart.cart_details.all().order_by('-date_added')

在这里,如果用户刚刚登录,将为他创建一个新的购物车.

并且,您可以通过以下方式将项目添加到用户的购物车:

# Assuming you have flower object and quantity=number of qty.
cart_item = CartDetail(flower=flower, cart=request.user.cart, quantity=quantity)

cart_item.save()

这种方法比你正在尝试的方法更清洁.我希望这有帮助.

我认为在这种情况下使用的正确架构如下:

class Cart(models.Model):
    user = models.OneToOneField(User, related_name='cart')        
    date_added = models.DateTimeField(auto_now_add=True, help_text="Date when cart is added.")
    date_modified = models.DateTimeField(auto_now=True, help_text="Date when cart is modified.")


class CartDetail(models.Model):
    cart = models.ForeignKey(Cart, related_name='cart_details')
    flower = models.ForeignKey(Flower)
    quantity = models.PositiveSmallIntegerField(help_text='Quantity to be purchased.')
    date_added = models.DateTimeField(auto_now_add=True,
                                      help_text="Date when this item is added.")
    date_modified = models.DateTimeField(auto_now=True, help_text="Date when this item is modified.")

因此,在这种情况下,您可以通过以下方式获取用户的购物车详情:

try:
    cart = request.user.cart
except Cart.DoesNotExist:
    cart = Cart.objects.create(user=request.user)
    cart_details = cart.cart_details.all().order_by('-date_added')

在这里,如果用户刚刚登录,将为他创建一个新的购物车.

并且,您可以通过以下方式将项目添加到用户的购物车:

# Assuming you have flower object and quantity=number of qty.
cart_item = CartDetail(flower=flower, cart=request.user.cart, quantity=quantity)

cart_item.save()

这种方法比你正在尝试的方法更清洁.我希望这有帮助.