Django通过循环遍历日期范围的每一天进行过滤

Question

我有一个名为Orders 的模型，用于电子商务网络应用程序，我想知道过去一年中每天的订单数量。所以我过滤了订单如下：

    product_orders = Order.objects.filter(
        ordered=True, variant__product=self, date__range=[(timezone.now() - timedelta(weeks=52)), timezone.now()])

我想从这个时间范围内循环遍历每一天并获取每天的订单数量，结果应该是这样的：

[
    {
        date: "2021-06-21",
        quantity: 6
    },
    {
        date: "2021-06-22",
        quantity: 0
    }
]

Order 模型上的日期字段称为 createdAt，它的 default=timezone.now 所以我想要一些汇总或注释过去一年每天创建的订单的内容

订单模型

class Order(models.Model):
    order_id = models.CharField(max_length=100, blank=True, null=True)
    user = models.ForeignKey(
        User, on_delete=models.CASCADE, related_name="orders")
    address = models.ForeignKey(
        Address, on_delete=models.SET_NULL, null=True, blank=True)
    variant = models.ForeignKey(
        "products.Variant", on_delete=models.CASCADE, related_name="orders")
    price = models.FloatField(blank=True, null=True)
    store = models.ForeignKey(
        "stores.Store", on_delete=models.CASCADE, related_name="orders", null=True, blank=True)
    # Cart
    in_cart = models.BooleanField(default=True)
    # Order
    order_group = models.ForeignKey(
        "OrderGroup", on_delete=models.CASCADE, related_name="orders", null=True, blank=True)
    ordered = models.BooleanField(default=False)
    ordered_date = models.DateTimeField(blank=True, null=True)
    cancelled = models.BooleanField(default=False)
    cancelled_date = models.DateTimeField(blank=True, null=True)
    # Return
    order_return_deadline = models.DateTimeField(blank=True, null=True)
    returning = models.BooleanField(default=False)
    returning_date = models.DateTimeField(blank=True, null=True)
    returned = models.BooleanField(default=False)
    returned_date = models.DateTimeField(blank=True, null=True)
    failed_return = models.BooleanField(default=False)
    # Shipping
    shipped = models.BooleanField(default=False)
    shipped_date = models.DateTimeField(blank=True, null=True)
    merchant_error = models.BooleanField(default=False)
    merchant_error_date = models.DateTimeField(blank=True, null=True)
    # Delivery
    delivered = models.BooleanField(default=False)
    delivered_date = models.DateTimeField(blank=True, null=True)
    failed_delivery = models.BooleanField(default=False)
    failed_delivery_date = models.DateTimeField(blank=True, null=True)
    created_at = models.DateTimeField(default=timezone.now)

    def __str__(self):
        return f"{self.user.last_name}'s Order"

其中数量为Order.objects.filter(...).count()

Answer 1

我只是简单地遍历过去一年的日期，然后过滤和计数

product_orders = Order.objects.filter(
            ordered=True,
            variant__product=self,
            ordered_date__range=(timezone.now()-timedelta(weeks=52), timezone.now()))

        result = []
        # looping through to get each day from now to a year ago
        for day in range(52*7+2):
            date = (timezone.now()-timedelta(days=day)).date().isoformat()
            result.append({
                "day": date,
                "quantity": product_orders.filter(ordered_date__date=date).count()
            })

这个解决方案给了我准确的结果，如果你有更有效的方法，我愿意接受。顺便说一句，我将 created_at 更改为 ordered_date

更高效的解决方案

        now_ = timezone.now
        product_orders = Order.objects.filter(
            ordered=True,
            variant__product=self,
            ordered_date__range=((now_()-timedelta(weeks=52)), now_())
        ).annotate(date=functions.TruncDay("ordered_date")).values("date").annotate(quantity=Count("id")).values("date", "quantity").order_by('date')
        temp = {po['date'].date(): po['quantity'] for po in product_orders}
        result = [
            {'date': (now_()-timedelta(days=dy)).date(),
             'quantity': temp.setdefault((now_()-timedelta(days=dy)).date(), 0)}
            for dy in range(52*7+1)
        ]

Answer 2

您可以使用Orders 的数量来注释您的Order：

from django.utils.timezone import now
from django.db.models import Count
from django.db.models.functions import TruncDate

now_ = now()

product_orders = Order.objects.filter(
    ordered=True,
    variant__product=self,
    created_at__range=(now_-timedelta(weeks=52)), now_())
).values(
    date=TruncDate('created_at__date')
).annotate(
    quantity=Count('pk')
).order_by('date')

这将返回带有字典作为项目的QuerySet，因此看起来像：

<QuerySet [
    {'date': date(2021, 6, 21), 'quantity': 6 },
    {'date': date(2021, 6, 23), 'quantity': 3 }
]>

如果某个日期没有订单，则该日期不会包含在输出中。因此，我们必须对数据进行后处理。

我们可以通过首先使用将日期映射到数量的字典来做到这一点，我们可以这样做：

temp = { po['date'].date(): po['quantity'] for po in product_orders }

然后将dates 的默认值设置为0，并将这些添加到result 列表中：

result = [
    {'date': (now_-timedelta(days=dy)).date(), 'quantity': temp.setdefault((now_-timedelta(days=dy)).date(), 0)}
    for dy in range(52*7+1)
]

然后result 包含带有date 和quantity 的字典列表。