Django Admin:多对多列表框没有显示带有参数

Question

我有以下型号:

class Message(models.Model):
    date = models.DateTimeField()
    user = models.ForeignKey(User)    
    thread = models.ForeignKey('self', blank=True, null=True)
    ...

class Forum(models.Model):
    name = models.CharField(max_length=24)
    messages = models.ManyToManyField(Message, through="Message_forum", blank=True, null=True)
    ...

class Message_forum(models.Model):
    message = models.ForeignKey(Message)
    forum = models.ForeignKey(Forum)
    status = models.IntegerField()
    position = models.IntegerField(blank=True, null=True)
    tags = models.ManyToManyField(Tag, blank=True, null=True)

在管理站点中,当我去添加/更改论坛时,我没有看到您期望的消息列表框.但是,如果我删除ManyToManyField声明中的'through'参数,它会显示出来.那是怎么回事？我已将所有三个模型(加上Tag)注册到admin.py中的管理站点.

TIA

Answer 1

文件说:

使用ManyToManyField的through参数指定中间模型时,管理员默认情况下不会显示窗口小部件.

但即使through定义了属性,也可能在管理员更改视图中显示M2M字段.

class ForumAdminForm(forms.ModelForm):
    mm = forms.ModelMultipleChoiceField(
        queryset=models.Message.objects.all(),
        widget=FilteredSelectMultiple(_('ss'), False, attrs={'rows':'10'}))

    def __init__(self, *args, **kwargs):
        if 'instance' in kwargs:
            initial = kwargs.setdefault('initial', {})
            initial['mm'] = [t.service.pk for t in kwargs['instance'].message_forum_set.all()]

        forms.ModelForm.__init__(self, *args, **kwargs)

    def save(self, commit=True):
        instance = forms.ModelForm.save(self, commit)

        old_save_m2m = self.save_m2m
        def save_m2m():
            old_save_m2m()

            messages = [s for s in self.cleaned_data['ss']]
            for mf in instance.message_forum_set.all():
                if mf.service not in messages:
                    mf.delete()
                else:
                    messages.remove(mf.service)

            for message in messages:
                Message_forum.objects.create(message=message, forum=instance)

        self.save_m2m = save_m2m

        return instance

    class Meta:
        model = models.Forum

class ForumAdmin(admin.ModelAdmin):
    form = ForumAdminForm

Answer 2

看看官方文档: