Django IndexError：从DeleteView中的空列表中弹出

Question

我正在尝试从Django应用程序的数据库中删除对象。

想法是从html文件中获取主要文件，并将其发布为表单。我不了解如何传递主键以正确的方式发布删除请求。

我在堆栈溢出，django doc和其他资源上都找到了有关基于类的视图DeleteView的所有知识，而没有弄清楚这是如何工作的。

例如为：Django delete FileField

How to delete a record in Django models?

Python Django delete current object

How to delete a record in Django models?

https://docs.djangoproject.com/en/2.2/topics/db/queries/

https://docs.djangoproject.com/en/2.2/ref/class-based-views/generic-editing/#django.views.generic.edit.DeleteView

在代码的主要摘要下面，如果您缺少所需的内容，请告诉我。

views.py

class SelectFileDelView(TemplateView):
    """
    This view is used to select a file from the list of files in the server.
    After the selection, it will send the file to the server.
    The server will then delete the file.
    """
    template_name = 'select_file_deletion.html'
    parser_classes = FormParser
    queryset = FileModel.objects.all()

    def get_context_data(self, **kwargs):
        """
        This function is used to render the list of files in the MEDIA_ROOT in the html template
        and to get the pk (primary key) of each file.
        """
        context = super().get_context_data(**kwargs)
        media_path = settings.MEDIA_ROOT
        myfiles = [f for f in listdir(media_path) if isfile(join(media_path, f))]
        pk_list = []
        for value in myfiles:
            pk = FileModel.objects.filter(file=value).values_list('pk', flat=True)
            pk_list.append(pk)
        file_and_pk = zip(myfiles, pk_list)
        context['filename'] = file_and_pk
        return context


class FileDeleteView(DeleteView):
    """
    This class contains the method to delete a file interacting directly with the API.
    DELETE requests are accepted.
    """
    model = FileModel
    fields = ['file']
    template_name = 'delete_success.html'
    success_url = '/delete_success/'

    def post(self, request):
        """
        This method is used to making predictions on audio files
        loaded with FileView.post
        """
        pk = request.POST.getlist('pk').pop()
        try:
            return Response(pk, status=status.HTTP_200_OK)
        except ValueError as err:
            return Response(str(err), status=status.HTTP_400_BAD_REQUEST)

select_file_deletion.html

{% extends "index.html" %}

{% block content %}
    <form action="/App/delete/" method="post" enctype="multipart/form-data">
        {% csrf_token %}
        {{ form.as_p }}
        <h5>Please select one file at a time from the list below to delete it from the server.</h5>
        {% for myfile, pk in filename %}
            <p>Are you sure you want to delete "{{ myfile }}"?</p>
            <input type="submit" value="Confirm">
            <input type="hidden" name="pk" value="{{ pk }}">
            <br>
        {% endfor %}
        <br>
    </form>
{% endblock %}

urls.py

urlpatterns = [

    # Url to select a file to be deleted and confirm the upload
    url('filedelete/', SelectFileDelView.as_view(), name='file_delete'),
    url('delete_success/(?P<pk>\d+)/$', FileDeleteView.as_view(), name='delete_success'),

]

models.py

"""
Models.py includes the database structure of the application.
"""

from django.db import models
from django.conf import settings
from django.dispatch import receiver
from django.db.models.signals import post_delete


class FileModel(models.Model):
    file = models.FileField(null=True, blank=True)
    timestamp = models.DateTimeField(auto_now_add=True)
    path = models.FilePathField(path=settings.MEDIA_ROOT, default=settings.MEDIA_ROOT)


@receiver(post_delete, sender=FileModel)
def submission_delete(sender, instance, **kwargs):
    """
    This function is used to delete attachments when a file object is deleted.
    Django does not do this automatically.
    """
    instance.file.delete(False)

ERROR：

IndexError at /App/delete/
pop from empty list
Request Method: POST
Request URL:    http://127.0.0.1:8000/App/delete/
Django Version: 2.2.4
Exception Type: IndexError
Exception Value:    
pop from empty list
Exception Location: /Users/marcogdepinto/PycharmProjects/DjangoRestDeepLearning/App/views.py in post, line 131
Python Executable:  /Users/marcogdepinto/anaconda3/bin/python
Python Version: 3.6.9

UPDATE1：html如下更改

<input type="hidden" name="pk" value="{{ pk }}">

这样做，我得到一个

AssertionError at /App/delete/
.accepted_renderer not set on Response

下面的完整回溯：

Environment:

Request Method: POST
Request URL: http://127.0.0.1:8000/App/delete/

Django Version: 2.2.4
Python Version: 3.6.9
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'rest_framework',
 'App',
 'debug_toolbar']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'debug_toolbar.middleware.DebugToolbarMiddleware']



Traceback:

File "/Users/marcogdepinto/anaconda3/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/Users/marcogdepinto/anaconda3/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  145.                 response = self.process_exception_by_middleware(e, request)

File "/Users/marcogdepinto/anaconda3/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  143.                 response = response.render()

File "/Users/marcogdepinto/anaconda3/lib/python3.6/site-packages/django/template/response.py" in render
  106.             self.content = self.rendered_content

File "/Users/marcogdepinto/anaconda3/lib/python3.6/site-packages/rest_framework/response.py" in rendered_content
  55.         assert renderer, ".accepted_renderer not set on Response"

Exception Type: AssertionError at /App/delete/
Exception Value: .accepted_renderer not set on Response

Answer 1

request.POST是表单输入的相应名称/值的键/值对的QueryDict。

[我认为问题在于您忘记在name输入中添加pk，所以当视图获取request.POST对象时，没有称为pk的键。

如果没有找到称为.getlist('arg')的键，并且没有给出默认值，则将导致您得到错误。[>

这应该可以解决您的问题：

arg
更新

我相信您得到的错误与您原来的问题无关，可能应该作为一个新问题提出。话虽如此，我仍然会尽力提供帮助，我只是没有使用DRF的经验。

根据<input type="hidden" name="pk" value="{{ pk }}"> ：

accepted_renderer

将用于呈现响应的呈现器实例。从视图返回响应之前，由APIView或@api_view自动设置。]

另外：

除非出于某种原因要大量定制REST框架，否则对于返回Response对象的视图，应始终使用API​​View类或@api_view函数。这样做可确保在视图返回视图之前，视图可以执行内容协商并为响应选择适当的渲染器。

我认为您最好的选择是使用docs装饰器（尽管我不确定这是否可以在基于分类的视图中使用。）>

@api_view