我有以下型号：
- class LibraryEntry(models.Model):
- player = models.ForeignKey(Player)
- player_lib_song_id = models.IntegerField()
- title = models.CharField(max_length=200)
- artist = models.CharField(max_length=200)
- album = models.CharField(max_length=200)
- track = models.IntegerField()
- genre = models.CharField(max_length=50)
- duration = models.IntegerField()
- is_deleted = models.BooleanField(default=False)
- class Meta:
- unique_together = ("player","player_lib_song_id")
- def __unicode__(self):
- return "Library Entry " + str(self.player_lib_song_id) + ": " + self.title
- class BannedSong(models.Model):
- lib_entry = models.ForeignKey(LibraryEntry)
- def __unicode__(self):
- return "Banned Library Entry " + str(self.lib_entry.title)
我想做这样的查询：
- banned_songs = BannedSong.objects.filter(lib_entry__player=activePlayer)
- available_songs = LibraryEntry.objects.filter(player=activePlayer).exclude(banned_songs)
基本上如果一首歌被禁止,我想把它从我的可用歌曲中排除.有没有办法在Django中这样做？
解决方法
- banned_song_ids = (BannedSong.objects.filter(lib_entry__player=activePlayer)
- .values_list('lib_entry',flat=True))
- available_songs = (LibraryEntry.objects.filter(player=activePlayer)
- .exclude('id__in' = banned_song_ids))
替代方案是：
- available_songs = (LibraryEntry.objects.filter(player=activePlayer)
- .filter(bannedsong__isnull = True))