django 中如何进行分组统计

参考 django 中如何进行分组统计？

from django.test import TestCase

# Create your tests here.

'''
https://www.v2ex.com/t/466327
如果你的 Model 定义了默认排序字段, 必须要加 order_by()

'''
import os

if __name__ == '__main__':
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "hey_star.settings")
    import django

    django.setup()

    from light.models import Light
    from django.db.models import Count

    # 新增归档字段查询
    # 比如查询 xxxx年x月发布的所有产品
    res = Light.objects.extra(
        select={"update_ym": "date_format(update_time, '%%Y-%%m-%%d')"}
    ).values("update_ym").annotate(c=Count("id")).values("update_ym", "c").order_by("update_ym")
    print(res)

Light的model 部分

class Light(models.Model):
    """
    灯具
    """
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    item_no = models.CharField(max_length=50, unique=True, verbose_name="编号")
    name = models.CharField(max_length=100, verbose_name="名称", null=True, blank=True)
    fob_ningbo_USD = models.CharField(max_length=20, verbose_name="FOB宁波(USD)")
    quotation_image = models.ImageField(upload_to="light/image", verbose_name="报价图片", null=True, blank=True)

    desc = RichTextUploadingField(verbose_name="产品具体描述")
    first_packing = models.CharField(max_length=50, verbose_name="第一包装尺寸(CM)")
    gross_weight = models.CharField(max_length=50, verbose_name="毛重(KG)")
    second_packing = models.CharField(max_length=50, verbose_name="第二包装尺寸(CM)")
    pks_qty = models.CharField(max_length=20, verbose_name="装箱数(PCS)", help_text="第二包装需要多少个第一包装")
    moq = models.CharField(max_length=20, verbose_name="MOQ(PCS)", help_text="最小起订量")

    is_new = models.BooleanField(default=False, verbose_name="是否新品")
    is_hot = models.BooleanField(default=False, verbose_name="是否热销")
    category = models.ForeignKey(LightCategory, on_delete=models.CASCADE, verbose_name="分类")
    add_time = models.DateTimeField(auto_now_add=True, verbose_name="添加时间")
    update_time = models.DateTimeField(auto_now=True, verbose_name="修改时间")

    class Meta:
        verbose_name = "灯具"
        verbose_name_plural = verbose_name
        ordering = ['-add_time']

    def __str__(self):
        return self.item_no

    def picture_img(self):
        if self.quotation_image:
            return mark_safe('<img src="%s" width="100px" />' % self.quotation_image.url)
        else:
            return '没有图片'

    picture_img.short_description = '缩略图'

    def delete(self, using=None, keep_parents=False):
        if os.path.isfile(self.quotation_image.path):
            os.remove(self.quotation_image.path)
        super(Light, self).delete(using, keep_parents)

    # 自定义 get_absolute_url 方法
    # 记得从 django.urls 中导入 reverse 函数
    def get_absolute_url(self):
        # return reverse("light:light-detail", kwargs={"pk": self.pk})
        # return reverse("light:thank_you")
        return reverse("light:light-detail", args=[str(self.id)])