Django的连接SQL查询有过滤器

例子：Django的连接SQL查询有过滤器

class Room(models.Model): 
    assigned_floor = models.ForeignKey(Floor, null=True, on_delete=models.CASCADE) 
    room_nr = models.CharField(db_index=True, max_length=4, unique=True, null=True) 
    locked = models.BooleanField(db_index=True, default=False) 
    last_cleaning = models.DateTimeField(db_index=True, auto_now_add=True, null=True) 
    ... 


class Floor(models.Model): 
    assigned_building = models.ForeignKey(Building, on_delete=models.CASCADE) 
    wall_color = models.CharField(db_index=True, max_length=255, blank=True, null=True) 
    ... 


class Building(models.Model): 
    name = models.CharField(db_index=True, max_length=255, unique=True, null=True) 
    number = models.PositiveIntegerField(db_index=True) 
    color = models.CharField(db_index=True, max_length=255, null=True) 
    ...

我要输出所有客房均可通过Building.number排序的表格。数据，我想打印每间客房： Building.number，Building.color，Building.name，Floor.wall_color，Room.last_cleaning

而且我想允许可选的过滤器： Room.locked室。最后清理Floor.wall_color Building.number Building.color

有一张桌子对我来说不是问题，但我不知道如何将它归档到三张桌子上。

kwargs = {'number': 123} 
kwargs['color'] = 'blue' 
all_buildings = Building.objects.filter(**kwargs).order_by('-number')

你能帮我吗？我是否需要编写原始SQL查询，还是可以使用Django模型查询API对它进行归档？

我使用最新的Django版本和PostgreSQL。

来源

2017-09-13 seeberg

不需要原始SQL：

room_queryset = Room.objects.filter(assigned_floor__wall_color='blue') 
                ^^ 
# A double unterscore declares the following attribute to be a field of the object referenced in the foregoing foreign key field. 

for room in room_queryset: 
    print(room.assigned_floor.assigned_building.number) 
    print(room.assigned_floor.assigned_building.color) 
    print(room.assigned_floor.assigned_building.name) 
    print(room.assigned_floor.wall_color) 
    print(room.last_cleaning)

来源

2017-09-13 07:03:54

Django的连接SQL查询有过滤器

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