Question

我正在尝试在1个查询中获取外键的外键，但无法正常工作

模型

date = "2019-07-13 14:40:50 GMT"

let a = {
  "status": "ok",
  "data": {
    "Gallery": {
      "gallery_id": "***ID***",
      "GalleryImage": [{
          "image_id": "***ID***",
          "gallery_id": "***ID***",
          "Image": {
            "image_id": "***ID***",
            "gallery_id": "***ID***",
            "ImageLink": {
              "link": "URLA"
            },
            "Iptc": {
              "sdate": "2019-07-11 14:40:50 GMT"
            }
          }
        },
        {
          "image_id": "***ID***",
          "gallery_id": "***ID***",
          "Image": {
            "image_id": "***ID***",
            "gallery_id": "***ID***",
            "ImageLink": {
              "link": "***URLB***"
            },
            "Iptc": {
              "sdate": "2019-07-12 14:40:50 GMT"
            }
          }
        },
        {
          "image_id": "***ID***",
          "gallery_id": "***ID***",
          "Image": {
            "image_id": "***ID***",
            "gallery_id": "***ID***",
            "ImageLink": {
              "link": "***URLC***"
            },
            "Iptc": {
              "sdate": "2019-07-13 14:40:50 GMT"
            }
          }
        }
      ]
    }
  }
}

let arr = a.data.Gallery.GalleryImage;

for (i = 0; i < arr.length; i++) {
  if (arr[i].Image && arr[i].Image.Iptc && arr[i].Image.Iptc.sdate && arr[i].Image.Iptc.sdate == date) {
    console.log(arr[i].Image.ImageLink.link)
  }

}

代码

当我拿到所有冰柜时，此方法有效

class Storage(models.Model):
    name = models.CharField(max_length=200,
                            null=False,
                            blank=False,
                            unique=True)

class Freezer(models.Model):
    name = models.CharField(max_length=200,
                            null=False,
                            blank=False,
                            unique=True)
    storage = models.ForeignKey(Storage,
                                models.CASCADE,
                                blank=True,
                                null=True,
                                related_name='freezer')

class Rack(models.Model):
    name = models.CharField(max_length=200,
                            null=False,
                            blank=False,
                            unique=True)
    freezer = models.ForeignKey(Freezer,
                                models.CASCADE,
                                blank=True,
                                null=True,
                                related_name='rack')

但是我无法获得有关此查询的信息

display_text = ", ".join([
    "<a href={}>{}</a>".format(
        reverse(
            'admin:{}_{}_change'.format("admin",
                                        "freezer"),
            args=(items.pk, )), items)
    for items in obj.freezer.all()
])
if display_text:
    return mark_safe(display_text)

有什么建议对不起我吗？

Answer 1

通过这种计算，您应该从所需的类（即机架）开始。

... for items in Rack.objects.filter(freezer__storage=obj)

（注意，通过将related_names设置为单数的“ rack”和“ freezer”，您已经使事情变得更加混乱。如果您必须将它们全部设置，我不建议这样做，应该至少使用复数名称。）

Django从queryset中的外键获取外键

1 个答案: