Django ManyToManyField through

1. 获取选择字段的choice

obj.get_fileld_display()

1. django中@property详解
   

   1. @property 可以将python定义的函数“当做”属性访问，从而提供更加友好访问方式，和java中的setter和getter类似。@xxx.setter 

2. ManyToManyField

   device_room = models.ManyToManyField(to='Device', through='DeviceRoom', through_fields=('room', 'device'))
   
   class DeviceRoom(models.Model):
       room = models.ForeignKey(Room, verbose_name='房间', on_delete=models.CASCADE, null=True)
       device = models.ForeignKey(Device, verbose_name='设备', on_delete=models.CASCADE, null=True)
       oneField= models.IntegerField('字段一', default=0)
   
   
   a.device_room.through.objects.all()
   
   In [29]:  a.device_room.through.objects.all()[:2]
   Out[29]: <QuerySet [<DeviceRoom: DeviceRoom object (47)>, <DeviceRoom: DeviceRoom object (60)>]>

    

3.