Django的NoneType'对象不是可迭代
问题描述:
我获得以下错误Django的NoneType'对象不是可迭代
对象“在/块/选择/ NoneType类型错误”不是可迭代
我该怎么办错了吗?
视图
def choices(request):
form = RoomLogChoices()
form.fields['choice'].choices = list()
for i in Room.objects.all():
form.fields['choice'].choices = form.fields['choice'].choices.append(
(
i.room_name,
list(
(o.id, o.room_value) for o in RoomLog.objects.filter(room=i).order_by('room')
)
)
)
形式
class RoomLogChoices(forms.ModelForm):
choice = forms.ModelChoiceField(
queryset=RoomLog.objects.all().order_by('room__room_name', 'room_value')
)
class Meta:
model = RoomLog
fields = '__all__'
编辑: 下面是我的模型的要求。我使用两种模式出于以下原因:Room和RoomLog。 RoomLog仅用于跟踪房间值更新的历史记录。
模型
class Room(models.Model):
room_name = models.CharField(max_length= 10)
room_value = models.PositiveSmallIntegerField(default=0)
flat = models.ForeignKey(Flat)
created_date = models.DateField(auto_now_add= True)
created_time = models.TimeField(auto_now_add= True)
def __init__(self, *args, **kwargs):
super(Room, self).__init__(*args, **kwargs)
self.value_original = self.room_value
def save(self, **kwargs):
with transaction.atomic():
response = super(Room, self).save(**kwargs)
if self.value_original != self.room_value:
room_log = RoomLog()
room_log.room = self
room_log.room_value = self.value_original
room_log.save()
return response
class Meta:
ordering = ('room_name',)
def __unicode__(self):
return self.room_name
class RoomLog(models.Model):
room = models.ForeignKey(Room)
room_value = models.PositiveSmallIntegerField(default=0)
update_date = models.DateField(auto_now_add= True)
update_time = models.TimeField(auto_now_add= True)
def __str__(self):
return '%s | %s | %s' % (self.room, self.update_date, self.update_time)
答
list.append “就地” 更新列表,并返回None
例如:
my_list = [1, 2, 3]
new_list = my_list.append(4)
print my_list, new_list
[1,2,3, 4]无
只需删除赋值语句。
def choices(request):
form = RoomLogChoices()
form.fields['choice'].choices = list()
for i in Room.objects.all():
form.fields['choice'].choices.append(
(
i.room_name,
list(
(o.id, o.room_value) for o in RoomLog.objects.filter(room=i).order_by('room')
)
)
)
我可以看到您的模型吗? – arcegk
在这行'form.fields ['choice']。choices = form.fields ['choice']。choices.append('你将'choices'设置为'None'。 –