选择共享ManyToMany关系的对象(Django)

Question

我有一个名为House的模型和另一个名为Location的模型，它们彼此之间具有ManyToMany关系。例如，房屋既可以位于location Brooklyn，也可以位于New York。

在我的New York页面上，我想显示“相关位置”或“附近位置”。我想选择与New York共享相同房屋的所有位置。

举个例子。

房屋A：Brooklyn，New York

房屋B：Manhattan，New York

我想从New York中选择位置Brooklyn，Manhattan。

我还想根据他们分享的房屋数量对他们进行排序。首先获取最“相关”的位置。

有什么想法吗？

Answer 1

以下是一些(未经测试的)代码，它们将为您提供如何实现此目标的线索：

# my_location is a Location object representing New York
similar_locations = {}

for house in House.ojects.filter(locations=my_location):  # get all houses in New York
    for house_location in house.locations.all():  # get all locations of all houses in New York
        # count the houses in each location
        if not house_location.pk in similar_locations:
            similar_locations[house_location.pk] = 1 
        else:
            similar_locations[house_locoation.pk] += 1

# sort the dictionary of locations by number of houses
# sorted_similar_locations will be a list of tuples sorted by the second element in each tuple.
import operator
sorted_similar_locations = reversed(sorted(similar_locations.items(), key=operator.itemgetter(1)))

# get Django objects of your locations (this depends on how many similar locations you expect. If it is a lot, this query is very inefficient)
locations = Location.objects.filter(pk__in=similar_locations.keys())

可能有更有效的方法来做到这一点。但这应该会给你一个好的开始！希望这能有所帮助。