django 视图没有返回 HttpResponse 对象。它返回 None 而不是

Posted 2023-02-26

【中文标题】django 视图没有返回 HttpResponse 对象。它返回 None 而不是

【英文标题】：django view didn't return an HttpResponse object. It returned None instead

【发布时间】：2014-11-14 09:28:58

【问题描述】：

这是我的看法：

def GeneralUserPictureChange(request, pk, username):
thumb = GeneralUser.objects.get(pk=pk)
if thumb.username == request.user:
    if request.method == 'POST':
        form = GeneralUserPictureChangeForm(request.POST, request.FILES)
        if form.is_valid():
            thumb.thumbnail = form.cleaned_data['thumbnail']
            thumb.save()
            return redirect("user_profile", pk, username)
        else:
            return render_to_response("gnu_picture_change.html", "form":form, "basic_info":thumb, context_instance=RequestContext(request))
    else:
        form = GeneralUserPictureChangeForm()
    return render_to_response("gnu_picture_change.html", "form":form, "basic_info":thumb, context_instance=RequestContext(request))

当我这样做时，错误没有返回 HttpResponse 对象。但是当我删除线 if thumb.username == request.user: 并继续进行适当的缩进它不会给出错误..

需要帮助...

【问题讨论】：

当if thumb.username == request.user: 为真并且代码朝那个方向发展时会发生什么？

问题是当if为假时会发生什么，没有返回

【参考方案1】：

您在此处比较 username field 和 user object：

if thumb.username == request.user:

thumb.username 可能会返回一个 string 像 'JohnDoe' request.user 返回一个对象，如：<User: johndoe>

所以if 似乎是假的ALLWAYS

要解决此问题，您应该这样做：

if thumb.username == request.user.username:

如果第一个条件为假会发生什么？您需要一个替代返回，与if thumb.username... 相同的缩进

---

你得到的是 None 而不是 HttpResponse，因为如果第一个 if 为假，你没有返回值

def GeneralUserPictureChange(request, pk, username):
thumb = GeneralUser.objects.get(pk=pk)
if thumb.username == request.user:
    if request.method == 'POST':
        form = GeneralUserPictureChangeForm(request.POST, request.FILES)
        if form.is_valid():
            thumb.thumbnail = form.cleaned_data['thumbnail']
            thumb.save()
            return redirect("user_profile", pk, username)
        else:
            return render_to_response("gnu_picture_change.html", "form":form, "basic_info":thumb, context_instance=RequestContext(request))
    else:
        form = GeneralUserPictureChangeForm()
    return render_to_response("gnu_picture_change.html", "form":form, "basic_info":thumb, context_instance=RequestContext(request))

# You need a return like this one, in case the first if is false
return render_to_response("gnu_picture_change.html", "Error":'Not valid username', context_instance=RequestContext(request))

【讨论】：

在最后的返回中你应该只返回一个错误变量或者初始化一个空表单