Warning: file_get_contents(/data/phpspider/zhask/data//catemap/2/django/20.json): failed to open stream: No such file or directory in /data/phpspider/zhask/libs/function.php on line 167

Warning: Invalid argument supplied for foreach() in /data/phpspider/zhask/libs/tag.function.php on line 1116

Notice: Undefined index: in /data/phpspider/zhask/libs/function.php on line 180

Warning: array_chunk() expects parameter 1 to be array, null given in /data/phpspider/zhask/libs/function.php on line 181
Python Django数据库:如何基于其他对象过滤对象';谁的领域?_Python_Django - Fatal编程技术网

Python Django数据库:如何基于其他对象过滤对象';谁的领域?

Python Django数据库:如何基于其他对象过滤对象';谁的领域?,python,django,Python,Django,在下面的代码中,如何筛选capital\u清单,以便仅返回首都的清单?另外,是否可以去掉中间的大写字母\u名称列表 capitals = City.objects.filter(status='capital') capitals_names = [capital.name for capital in capitals] capital_listings = Listing.objects.filter #??? 型号: class Listing(models.Model): ci

在下面的代码中,如何筛选
capital\u清单
,以便仅返回首都的清单?另外,是否可以去掉中间的
大写字母\u名称
列表

capitals = City.objects.filter(status='capital')
capitals_names = [capital.name for capital in capitals]
capital_listings = Listing.objects.filter #???
型号:

class Listing(models.Model):
    city = models.CharField(max_length = 30, default = 'placeholder')
    date_added = models.DateTimeField()

    def __str__(self):
        return self.name

class City(models.Model):
    name = models.CharField(max_length = 30, default = 'placeholder')
    status = models.CharField(max_length = 30, default = 'placeholder')

    def __str__(self):
        return self.name

如果您将
Listings.city
更改为foreignkey关系,则只需一步即可完成查询

class City(models.Model):
    name = models.CharField(max_length = 30, default = 'placeholder')
    status = models.CharField(max_length = 30, default = 'placeholder')

class Listing(models.Model):
    city = models.ForeignKey(City, on_delete=models.CASCADE)


capital_listings = Listing.objects.filter(city__status='capital')
这些文件对此进行了解释:


您在这里不使用外键的原因是什么?@JonClements:没有特别的原因。在这种情况下,我该如何应用它呢?Django教程相当不错——如果你看看上面@HåkenLid发布的链接和其中的例子——这将解释你需要的一切(可能还有更多有用的东西)
class City(models.Model):
    name = models.CharField(max_length = 30, default = 'placeholder')
    status = models.CharField(max_length = 30, default = 'placeholder')

class Listing(models.Model):
    city = models.ForeignKey(City, on_delete=models.CASCADE)


capital_listings = Listing.objects.filter(city__status='capital')