View 没有返回 HttpResponse 对象.它返回 None 代替 [英] View didn't return an HttpResponse object. It returned None instead

问题描述

下面的视图在使用 POST 方法时给了我错误.我正在尝试将模型数据加载到表单中，允许用户进行编辑，然后更新数据库.当我尝试保存更改时，出现上述错误.

The view below is gives me the error when using the POST method. I'm trying to load the model data into a form, allow the user to edit, and then update the database. When I try to Save the changes I get the above error.

def edit(request, row_id):
    rating = get_object_or_404(Rating, pk=row_id)
    context = {'form': rating}
    if request.method == "POST":
        form = RatingForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('home.html')
    else:
        return render(
            request,
            'ratings/entry_def.html',
            context
        )

这是来自终端的跟踪.

[15/Apr/2016 22:44:11] "GET / HTTP/1.1" 200 1554
[15/Apr/2016 22:44:12] "GET /rating/edit/1/ HTTP/1.1" 200 919
Internal Server Error: /rating/edit/1/
Traceback (most recent call last):
   File "/Users/michelecollender/ENVlag/lib/python2.7/site-packages/django/core/handlers/base.py", line 158, in get_response
    % (callback.__module__, view_name))
ValueError: The view ratings.views.edit didn't return an HttpResponse object. It returned None instead.

推荐答案

如果 form.is_valid() 你正在重定向但是表单无效怎么办?在这种情况下没有执行任何代码?没有代码.当函数没有显式返回值时，期望返回值的调用者被赋予 None.因此错误.

You are redirecting if form.is_valid() but what about the form is invalid? There isn't any code that get's executed in this case? There's no code for that. When a function doesn't explicitly return a value, a caller that expects a return value is given None. Hence the error.

你可以试试这样的:

def edit(request, row_id):
    rating = get_object_or_404(Rating, pk=row_id)
    context = {'form': rating}
    if request.method == "POST":
        form = RatingForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('home.html')
        else :
            return render(request, 'ratings/entry_def.html', 
                          {'form': form})
    else:
        return render(
            request,
            'ratings/entry_def.html',
            context
        )

这将导致表单再次显示给用户，如果您对模板进行了正确编码，它将显示哪些字段无效.

This will result in the form being displayed again to the user and if you have coded your template correctly it will show which fields are invalid.

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