4

我有两个视图，一个在表单无效时尝试添加到 POST 数据时工作正常，另一个在尝试做同样的事情时给我一个“这个 QueryDict 实例是不可变的”错误。我知道这些观点一开始就太相似了，无法将它们结合起来……但我想首先了解导致其中一个失败的区别是什么。

此视图工作正常：

@login_required
def url_parse(request):
    cu = request.user
    if request.method == 'POST':
        form = UrlBragForm(request.POST, request.FILES)
        if form.is_valid():
            t = handle_image_upload(form.cleaned_data['image'],cu.pk,'url')
            if t:
                b = Brag()
                b.user = cu
                b.image = t
                b.url = form.cleaned_data['url']
                b.description = form.cleaned_data['brag']
                b.active = True
                b.timestamp = time.time()
                b.save()
                tags = parse_tags(form.cleaned_data['brag'])
                if tags:
                    for tg in tags:
                        b.tags.add(tg)
            else:
                errors = form._errors.setdefault("image", ErrorList())
                errors.append(u"There was an issue with your image.  Please try again.")
        else:
            clean = cleanMessage(request.POST['brag'])
            if clean != 'is_clean':
                request.POST['brag'] = clean
    else:
        form = UrlBragForm()
    return render_to_response('brag/url_brag.html', {'form':form,}, context_instance=RequestContext(request))

但是当视图无效时，当尝试用“干净”数据填充 request.POST['brag'] 时，这个视图给了我一个“这个 QueryDict 实例是不可变的”：

@login_required
def brag_add_image(request):
    cu = request.user
    if request.method == 'POST':
        form = ImageAddBragForm(request.POST, request.FILES)
        if form.is_valid():
            t = handle_image_upload(form.cleaned_data['image'],cu.pk,'url')
            if t:
                b = Brag()
                b.user = cu
                b.image = t
                b.description = form.cleaned_data['brag']
                b.active = True
                b.timestamp = time.time()
                b.save()
                b.url = 'http://%s%s' % (Site.objects.get_current().domain, reverse('image_display', args=(b.pk,)))
                b.save()
                tags = parse_tags(form.cleaned_data['brag'])
                if tags:
                    for tg in tags:
                        b.tags.add(tg)
            else:
                errors = form._errors.setdefault("image", ErrorList())
                errors.append(u"There was an issue with your image.  Please try again.")
        else:
            clean = cleanMessage(request.POST['brag'])
            if clean != 'is_clean':
                request.POST['brag'] = clean
    else:
        form = ImageAddBragForm()
    return render_to_response('brag/image_brag_add.html', {'form':form,}, context_instance=RequestContext(request))

这是要求的回溯：

Traceback:
File "site/src/django/django/core/handlers/base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "site/src/django/django/contrib/auth/decorators.py" in _wrapped_view
  20.                 return view_func(request, *args, **kwargs)
File "site/brag/views.py" in brag_add_image
  241.                 request.POST['brag'] = clean
File "site/src/django/django/http/__init__.py" in __setitem__
  439.         self._assert_mutable()
File "site/src/django/django/http/__init__.py" in _assert_mutable
  436.             raise AttributeError("This QueryDict instance is immutable")

Exception Type: AttributeError at /brag/brag_add_image/
Exception Value: This QueryDict instance is immutable
4

1 回答 1

4

弄清楚了。这是因为我在模板中调用表单的方式。如果您将 enctype 更改为 multipart，您将不再收到错误消息。这绝不是一个修复，你应该看看在你的表单类而不是视图中这样做。但我想弄清楚为什么它以一种方式而不是另一种方式起作用。 

<form action="." method="post" class="genForm" enctype="multipart/form-data">

对比

<form action="." method="post" class="genForm">

这似乎是 Django 中的一个错误（为什么不在这两种情况下都强制执行？）

由于这个答案似乎有些混乱，我这里是一个更简单的例子，它显示了同样的结果：

看法 ：

def testit(request):
    if request.method == "POST":
        form = testForm(request.POST, request.FILES)
        clean = 'Going to stuff post data with this string'
        if form.is_valid():
            print 'valid'
            request.POST['testOne'] = clean
        else:
            print 'not valid'
            request.POST['testOne'] = clean
    else:
        form = testForm()
    return render_to_response('brag_board/test.html', {'form':form}, context_instance=RequestContext(request))

形式：

class testForm(forms.Form):
    testOne = forms.CharField(required=True)
    testTwo = forms.CharField(required=True)

给出错误的模板：

<!DOCTYPE html>
<html>
<head>
    <title>test</title>
</head>
<body>

<form action="." method="post" class="genForm">
{{ form }}
{% csrf_token %}
<button type="submit" name="action" value="addnewsletter">test</button>
</form>

</body>
</html>

不报错的模板：

<!DOCTYPE html>
<html>
<head>
    <title>test</title>
</head>
<body>

<form action="." method="post" class="genForm" enctype="multipart/form-data">
{{ form }}
{% csrf_token %}
<button type="submit" name="action" value="addnewsletter">test</button>
</form>

</body>
</html>
于 2013-08-31T16:46:25.313 回答