Django用户编辑个人资料时出现'NoneType'不可迭代错误求助

我是一名Django及Web框架领域的初级开发者，正在用Django 3开发共享办公空间管理系统。目前遇到一个棘手的问题：用户在个人资料页面点击编辑时触发了TypeError: 'NoneType' object is not iterable错误，但通过admin后台编辑个人资料完全正常。

报错回溯 #

Traceback (most recent call last):
File "/home/maha/venv/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
response = get_response(request)
File "/home/maha/venv/lib/python3.7/site-packages/django/core/handlers/base.py", line 115, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/home/maha/venv/lib/python3.7/site-packages/django/core/handlers/base.py", line 113, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/maha/venv/lib/python3.7/site-packages/django/contrib/auth/decorators.py", line 21, in _wrapped_view
return view_func(request, *args, **kwargs)
File "/home/maha/venv/nadine/member/views/profile.py", line 232, in edit_profile
return render(request, 'member/profile/profile_edit.html', context)
File "/home/maha/venv/lib/python3.7/site-packages/django/shortcuts.py", line 19, in render
content = loader.render_to_string(template_name, context, request, using=using)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/loader.py", line 62, in render_to_string
return template.render(context, request)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/backends/django.py", line 61, in render
return self.template.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 171, in render
return self._render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/test/utils.py", line 95, in instrumented_test_render
return self.nodelist.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 936, in render
bit = node.render_annotated(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 903, in render_annotated
return self.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/loader_tags.py", line 150, in render
return compiled_parent._render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/test/utils.py", line 95, in instrumented_test_render
return self.nodelist.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 936, in render
bit = node.render_annotated(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 903, in render_annotated
return self.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/loader_tags.py", line 62, in render
result = block.nodelist.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 936, in render
bit = node.render_annotated(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 903, in render_annotated
return self.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/loader_tags.py", line 62, in render
result = block.nodelist.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 936, in render
bit = node.render_annotated(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 903, in render_annotated
return self.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/loader_tags.py", line 62, in render
result = block.nodelist.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 936, in render
bit = node.render_annotated(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 903, in render_annotated
return self.render(context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 992, in render
return render_value_in_context(output, context)
File "/home/maha/venv/lib/python3.7/site-packages/django/template/base.py", line 971, in render_value_in_context
value = str(value)
File "/home/maha/venv/lib/python3.7/site-packages/django/utils/html.py", line 373, in <lambda>
klass.__str__ = lambda self: mark_safe(klass_str(self))
File "/home/maha/venv/lib/python3.7/site-packages/django/forms/boundfield.py", line 33, in __str__
return self.as_widget()
File "/home/maha/venv/lib/python3.7/site-packages/django/forms/boundfield.py", line 89, in as_widget
attrs = self.build_widget_attrs(attrs, widget)
File "/home/maha/venv/lib/python3.7/site-packages/django/forms/boundfield.py", line 224, in build_widget_attrs
if widget.use_required_attribute(self.initial) and self.field.required and self.form.use_required_attribute:
File "/home/maha/venv/lib/python3.7/site-packages/django/forms/widgets.py", line 699, in use_required_attribute
first_choice = next(iter(self.choices), None)
File "/home/maha/venv/lib/python3.7/site-packages/django/forms/fields.py", line 757, in __iter__
yield from self.choices_func()
Exception Type: TypeError at /member/profile/salem_otaibi/edit/
Exception Value: 'NoneType' object is not iterable

相关视图代码（profile.py） #

@login_required
def edit_profile(request, username):
    user = get_object_or_404(User, username=username)
    if not user == request.user:
        if not request.user.is_staff:
            return HttpResponseRedirect(reverse('member:profile:view', kwargs={'username': request.user.username}))
    LinkFormSet = formset_factory(LinkForm, formset=BaseLinkFormSet)
    user_links = user.profile.websites.all()
    link_data = [{'url_type': l.url_type, 'url': l.url, 'username': user.username} for l in user_links]
    if request.method == 'POST':
        profile_form = EditProfileForm(request.POST)
        link_formset = LinkFormSet(request.POST)
        profile_form.public_profile = request.POST['public_profile']
        if profile_form.is_valid():
            if link_formset.is_valid():
                if request.POST.get('password-create') == request.POST.get('password-confirm'):
                    pwd = request.POST.get('password-create')
                    if len(pwd.strip()) > 0:
                        if pwd.strip() == pwd and len(pwd) > 7:
                            profile_form.save()
                            user.set_password(pwd)
                            user.save()
                            return HttpResponseRedirect(reverse('member:profile:view', kwargs={'username': user.username}))
                        else:
                            messages.error(request, 'Your password must be at least 8 characters long.')
                    else:
                        for link in link_data:
                            del_url = link.get('url')
                            user.profile.websites.filter(url=del_url).delete()
                        for link_form in link_formset:
                            if not link_form.cleaned_data.get('username'):
                                link_form.cleaned_data['username'] = user.username
                            try:
                                if link_form.is_valid():
                                    url_type = link_form.cleaned_data.get('url_type')
                                    url = link_form.cleaned_data.get('url')
                                    if url_type and url:
                                        link_form.save()
                            except Exception as e:
                                messages.add_message(request, messages.ERROR, "Could not save: %s" % str(e))
                        profile_form.save()
                        return HttpResponseRedirect(reverse('member:profile:view', kwargs={'username': user.username}))
                else:
                    messages.error(request,'The entered passwords do not match. Please try again.')
            else:
                messages.error(request, 'There was an error saving your websites. Please make sure they have a valid URL and URL type.')
    else:
        link_formset = LinkFormSet(initial=link_data)
        profile = user.profile
        emergency_contact = user.get_emergency_contact()
        profile_form = EditProfileForm(initial={'username': user.username, 'first_name': user.first_name, 'last_name': user.last_name, 'email': user.email, 'phone': profile.phone, 'phone2': profile.phone2, 'address1': profile.address1, 'address2': profile.address2, 'city': profile.city, 'state': profile.state, 'zipcode': profile.zipcode, 'url_personal': profile.url_personal, 'url_professional': profile.url_professional, 'url_facebook': profile.url_facebook, 'url_twitter': profile.url_twitter, 'url_linkedin': profile.url_linkedin, 'url_github': profile.url_github, 'bio': profile.bio, 'photo': profile.photo, 'public_profile': profile.public_profile, 'gender': profile.gender, 'pronouns': profile.pronouns, 'howHeard': profile.howHeard, 'industry': profile.industry, 'neighborhood': profile.neighborhood, 'has_kids': profile.has_kids, 'self_employed': profile.self_employed, 'emergency_name': emergency_contact.name, 'emergency_relationship': emergency_contact.relationship, 'emergency_phone': emergency_contact.phone, 'emergency_email': emergency_contact.email, })
    context = {'user': user, 'profile_form': profile_form, 'link_formset': link_formset}
    return render(request, 'member/profile/profile_edit.html', context)

恳请各位大佬帮忙排查一下问题，谢谢！

内容的提问来源于stack exchange，提问作者midna3689