如何始终过滤对象请求上的字段

Question

我有两个型号:

class Album(models.Model):
#Attributes
title = models.CharField(max_length=200)
displayed = models.BooleanField()
created_on = models.DateTimeField(auto_now_add=True)

class Photos(models.Model):
#Attributes
title = models.CharField(max_length=500)
link = models.CharField(max_length=500)
album = models.ForeignKey(Album, unique=False, verbose_name=_('album'))

def upload_path(self, filename):
    return 'upload/photos/%s/%s' % (self.id, filename)

def upload_path_thumbnail(self, filename):
    return 'upload/photos/%s/%s' % (self.id, "thumnail_" +filename)

thumbnail = models.ImageField(upload_to=upload_path_thumbnail)                             
photo = models.ImageField(upload_to=upload_path)
created_on = models.DateTimeField(auto_now_add=True)
displayed = models.BooleanField() 

我想强制,当我选择照片时,总是过滤显示= 1.

谢谢

Answer 1

使用自定义管理器:

class DisplayedPhotoManager(models.Manager):
    def get_queryset(self):
        return super(DisplayedPhotoManager, self).get_queryset().filter(displayed=1)

class Photos(models.Model):
    objects =  DisplayedPhotoManager()   
    ...

这将覆盖标准的"对象"管理器(这可能是危险的).

一个更好的模式通常是:

class DisplayedPhotoManager(models.Manager):
    def get_queryset(self):
        return super(DisplayedPhotoManager, self).get_queryset().filter(displayed=1)

class Photos(models.Model):
    objects = models.Manager()
    displayed = DisplayedPhotoManager()   
    ...

并使用'显示'而不是'对象':

Photo.displayed.all()