如何使用ManyToMany字段填充默认表单数据？
好吧，我在谷歌和Django的文档上搜索了超过两个小时（还有在freenode的IRC频道），但就是搞不明白这个问题。
基本上，我有一个叫做 Room 的模型，下面是它的定义：
class Room(models.Model):
"""
A `Partyline` room. Rooms on the `Partyline`s are like mini-chatrooms. Each
room has a variable amount of `Caller`s, and usually a moderator of some
sort. Each `Partyline` has many rooms, and it is common for `Caller`s to
join multiple rooms over the duration of their call.
"""
LIVE = 0
PRIVATE = 1
ONE_ON_ONE = 2
UNCENSORED = 3
BULLETIN_BOARD = 4
CHILL = 5
PHONE_BOOTH = 6
TYPE_CHOICES = (
('LR', 'Live Room'),
('PR', 'Private Room'),
('UR', 'Uncensored Room'),
)
type = models.CharField('Room Type', max_length=2, choices=TYPE_CHOICES)
number = models.IntegerField('Room Number')
partyline = models.ForeignKey(Partyline)
owner = models.ForeignKey(User, blank=True, null=True)
bans = models.ManyToManyField(Caller, blank=True, null=True)
def __unicode__(self):
return "%s - %s %d" % (self.partyline.name, self.type, self.number)
我还有一个 forms.py 文件，里面有一个 ModelForm，用来表示我的 Room 模型：
from django.forms import ModelForm
from partyline_portal.rooms.models import Room
class RoomForm(ModelForm):
class Meta:
model = Room
我正在创建一个视图，让管理员可以编辑特定的 Room 对象。到目前为止，我的视图是这样的：
def edit_room(request, id=None):
"""
Edit various attributes of a specific `Room`. Room owners do not have
access to this page. They cannot edit the attributes of the `Room`(s) that
they control.
"""
room = get_object_or_404(Room, id=id)
if not room.is_owner(request.user):
return HttpResponseForbidden('Forbidden.')
if is_user_type(request.user, ['admin']):
form_type = RoomForm
elif is_user_type(request.user, ['lm']):
form_type = LineManagerEditRoomForm
elif is_user_type(request.user, ['lo']):
form_type = LineOwnerEditRoomForm
if request.method == 'POST':
form = form_type(request.POST, instance=room)
if form.is_valid():
if 'owner' in form.cleaned_data:
room.owner = form.cleaned_data['owner']
room.save()
else:
defaults = {'type': room.type, 'number': room.number, 'partyline': room.partyline.id}
if room.owner:
defaults['owner'] = room.owner.id
if room.bans:
defaults['bans'] = room.bans.all() ### this does not work properly!
form = form_type(defaults, instance=room)
variables = RequestContext(request, {'form': form, 'room': room})
return render_to_response('portal/rooms/edit.html', variables)
现在，这个视图在我查看页面时工作得很好。它显示了所有表单属性，所有默认值都填好了（当用户进行GET请求时）……除了 ManyToMany 字段 'bans' 的默认值。
简单来说，如果管理员点击一个 Room 对象进行编辑，他们会看到所有 Room 的默认值，除了 'bans'。无论我怎么做，我都找不到办法让Django显示当前被“禁用的用户”对于这个 Room 对象。这里是需要修改的代码行（来自视图）：
defaults = {'type': room.type, 'number': room.number, 'partyline': room.partyline.id}
if room.owner:
defaults['owner'] = room.owner.id
if room.bans:
defaults['bans'] = room.bans.all() ### this does not work properly!
我肯定还有其他语法需要用来指定 'bans' 字段的默认值。我真的为这个问题抓狂，非常希望能得到一些帮助。
谢谢！
更新
lazerscience 实际上在他的评论中帮我找到了解决方案。基本上，它的工作原理是如果你传递一个主键的列表。为了让它工作，我必须把：
if room.bans:
defaults['bans'] = room.bans.all() ### this does not work properly!
改成
if room.bans:
defaults['bans'] = [b.pk for b in room.bans.all()]
然后就好了，立刻开始工作了（当我查看页面时，它会显示一个可选择的 Caller 列表，已经被禁用的呼叫者会被高亮显示（选中状态）。