Django 查询集连接表

Question

我真的被合并两个表所困扰。

我有表格 Item 和 Transactions

class Item(models.Model):
    category_choices = []
    item_id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=100)
    description = models.TextField()
    category = models.CharField(max_length=100, choices=category_choices)
    image = models.ImageField(upload_to='media')
    stock = models.IntegerField()
    price = models.DecimalField(max_digits=10, decimal_places=2)
    date_added = models.DateTimeField(default=timezone.now())

class Transactions(models.Model):
    transaction_id = models.AutoField(primary_key=True)
    order_id = models.UUIDField()
    item_id = models.ForeignKey(Item, on_delete=models.CASCADE, related_name='transactions')
    quantity = models.IntegerField()
    price = models.DecimalField(max_digits=10, decimal_places=2)
    transaction_date = models.DateTimeField(auto_now_add=True)
    username = models.CharField(max_length=100)
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    address_str = models.CharField(max_length=100)
    address_plz = models.CharField(max_length=100)
    address_place = models.CharField(max_length=100)
    address_country = models.CharField(max_length=100, choices=[(name[1], name[1]) for name in countries])

现在我想用来自项目模型的交易、图像和项目信息来渲染模板。我正在尝试使用 prefetch_related，但是 rit 不起作用，我不明白应该如何解决。

def order_history(request):
    if request.user.is_authenticated:
        transaction = Transactions.objects.order_by('-transaction_date').\
            filter(username=request.user).prefetch_related('item')

        context = {'orders': transaction}
        template_name = 'retail/order_history.html'
        return render(request, template_name, context=context)
    else:
        raise Http404('You are not authorised')

Answer 1

在您的交易表中，将您的项目列命名为 item 而不是 item_id：

item = models.ForeignKey(Item, on_delete=models.CASCADE, related_name='transactions')

那么您的prefetch_related("item") 将按预期工作。