FormView一直让我无效

Question

我正在尝试将功能视图转换为类视图。函数视图完美无缺，但我似乎无法通过form_view的form_valid函数。

以下是基于功能的视图：

@login_required
def add_friends(request, tab_name_slug):
    # twitter friends into a list
    friends = [u.screen_name for u in tweepy.Cursor(api.friends).items()]

    tabs = get_or_none(Tab, user=request.user, slug=tab_name_slug)
    user_tab = get_or_none(FriendsList, user=request.user, tab=tabs)
    tab_friends =  ast.literal_eval((user_tab.flist).decode()) if user_tab != None else None 
    # friendlist form
    if request.method == 'POST':
        form = FriendsListForm(request.POST)
        if form.is_valid():
            # Delete existing list
            if user_tab != None:
                user_tab.delete()

            flist = form.save(commit=False)
            flist.tab = tabs
            flist.user = request.user
            flist.save()
            #  New Added Friends into Category 
            tabs = get_or_none(Tab, user=request.user, slug=tab_name_slug)
            user_tab = get_or_none(FriendsList, user=request.user, tab=tabs)
            tab_friends =  ast.literal_eval((user_tab.flist).decode()) if user_tab != None else None 
            # delete friends that aren't in the friend category list 

            [friend.delete() for friend in Friend.objects.filter(friend=request.user, tab=tabs)]
            [Friend.objects.create(friend=request.user, tab=tabs, name= new_friend) for new_friend in tab_friends]

        else:
            print form.errors
    else:
        form = FriendsListForm()

    context_dict = {'form':form, 'tabs': tabs, 'friends': friends, 'tab_friends': tab_friends}

    return render(request, 'ttapp/add_friends.html', context_dict)

以下是基于类的视图：

class AddFriendsView(FormView, LoginRequiredMixin):
    template_name = "ttapp/add_friends.html"
    form_class = FriendsListForm
    success_url = '/home/'

    def get_context_data(self, *args, **kwargs):
        context = super(AddFriendsView, self).get_context_data(*args, **kwargs)
        friends = [u.screen_name for u in tweepy.Cursor(api.friends).items()]
        tabs = get_or_none(Tab, user=self.request.user, slug=self.kwargs["tab_name_slug"])
        user_tab = get_or_none(FriendsList, user=self.request.user, tab=tabs)
        tab_friends =  ast.literal_eval((user_tab.flist).decode()) if user_tab != None else None 

        context = {'tabs':tabs, 'friends':friends, 'tab_friends': tab_friends}
        return context

    def form_valid(self, form):
        print "valid"

        return super(AddFriendsView, self).form_valid(form)

    def form_invalid(self, form):

        print "invalid"
        return self.render_to_response(self.get_context_data(form=form))

编辑：

找出类视图没有显示像在函数视图中那样的字段（使用{{form.as_p}}从django表单自动生成）。

就是这样：

<textarea cols="40" id="id_flist" name="flist" rows="10" style="display: none;"></textarea>