Django 2.0 教程 - 属性错误在 /polls/1/vote/ 'ReverseManyToOneDescriptor'对象没有属性'get'

Question

我以前在SE上遇到过这个错误，但它往往是以前版本的Django——我对Django的工作原理没有很好的理解。我已经进入了本教程的第 4 部分，并且它一直工作到本教程。我真的不确定我做错了什么 - 此时大部分都是从教程中复制/粘贴的，看看这是否会使其工作。我不完全是python saavy，所以如果有人能用相当简单的英语解释这个问题，我将不胜感激。我知道这个问题与 viws 中的第 30 行有关，在"投票"部分 -

def vote(request, question_id):
try:
selected_choice = Question.choice_set.get(pk=request.POST['choice'])
except (KeyError, Choice.DoesNotExist):
# Redisplay the question voting form.
return render(request, 'polls/detail.html', {
'question': question,
'error_message': "You didn't select a choice.",
})
else:
selected_choice.votes += 1
selected_choice.save()
# Always return an HttpResponseRedirect after successfully dealing
# with POST data. This prevents data from being posted twice if a
# user hits the Back button.
return HttpResponseRedirect(reverse('polls:results', args=(question.id,))) 

谢谢SE。

错误代码：

AttributeError at /polls/1/vote/
'ReverseManyToOneDescriptor' object has no attribute 'get'
Request Method: POST
Request URL:    http://localhost:8000/polls/1/vote/
Django Version: 2.0
Exception Type: AttributeError
Exception Value:    
'ReverseManyToOneDescriptor' object has no attribute 'get'
Exception Location: /Users/coreydickinson/mysite/DJDev/env1/mysite2/mysite3/polls/views.py in vote, line 30
Python Executable:  /Users/coreydickinson/mysite/DJDev/env1/bin/python
Python Version: 3.6.5
Python Path:    
['/Users/coreydickinson/mysite/DJDev/env1/mysite2/mysite3',
'/Users/coreydickinson/mysite/DJDev/env1/lib/python36.zip',
'/Users/coreydickinson/mysite/DJDev/env1/lib/python3.6',
'/Users/coreydickinson/mysite/DJDev/env1/lib/python3.6/lib-dynload',
'/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6',
'/Users/coreydickinson/mysite/DJDev/env1/lib/python3.6/site-packages']
Server time:    Sat, 26 May 2018 03:16:49 +0000

Environment:

Request Method: POST
Request URL: http://localhost:8000/polls/1/vote/
Django Version: 2.0
Python Version: 3.6.5
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'polls.apps.PollsConfig']
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']

Traceback:
File "/Users/coreydickinson/mysite/DJDev/env1/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
35.             response = get_response(request)
File "/Users/coreydickinson/mysite/DJDev/env1/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
128.                 response = self.process_exception_by_middleware(e, request)
File "/Users/coreydickinson/mysite/DJDev/env1/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
126.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/coreydickinson/mysite/DJDev/env1/mysite2/mysite3/polls/views.py" in vote
30.         selected_choice = Question.choice_set.get(pk=request.POST['choice'])
Exception Type: AttributeError at /polls/1/vote/
Exception Value: 'ReverseManyToOneDescriptor' object has no attribute 'get'

这是我对各种文件的代码：

投票/网址：

from django.urls import path
from . import views
app_name = 'polls'
urlpatterns = [
path('', views.IndexView.as_view(), name='index'),
path('<int:pk>/', views.DetailView.as_view(), name='detail'),
path('<int:pk>/results/', views.ResultsView.as_view(), name='results'),
path('<int:question_id>/vote/', views.vote, name='vote'),
]

民意调查/视频：

from django.urls import reverse
from django.views import generic
from .models import Choice, Question

class IndexView(generic.ListView):
template_name = 'polls/index.html'
context_object_name = 'latest_question_list'
def get_queryset(self):
"""Return the last five published questions."""
return Question.objects.order_by('-pub_date')[:5]

class DetailView(generic.DetailView):
model = Question
template_name = 'polls/details.html'

class ResultsView(generic.DetailView):
model = Question
template_name = 'polls/results.html'

def vote(request, question_id):
try:
selected_choice = Question.choice_set.get(pk=request.POST['choice'])
except (KeyError, Choice.DoesNotExist):
# Redisplay the question voting form.
return render(request, 'polls/detail.html', {
'question': question,
'error_message': "You didn't select a choice.",
})
else:
selected_choice.votes += 1
selected_choice.save()
# Always return an HttpResponseRedirect after successfully dealing
# with POST data. This prevents data from being posted twice if a
# user hits the Back button.
return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

投票/管理员：

from django.contrib import admin
from .models import Question
admin.site.register(Question)
polls/urls:
from django.urls import path
from . import views
app_name = 'polls'
urlpatterns = [
path('', views.IndexView.as_view(), name='index'),
path('<int:pk>/', views.DetailView.as_view(), name='detail'),
path('<int:pk>/results/', views.ResultsView.as_view(), name='results'),
path('<int:question_id>/vote/', views.vote, name='vote'),
]

polls/templates/polls/details.html：

<h1>{{ question.question_text }}</h1>
<ul>
{% for choice in question.choice_set.all %}
<li>{{ choice.choice_text }}</li>
{% endfor %}
</ul>
<h1>{{ question.question_text }}</h1>
{% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}
<form action="{% url 'polls:vote' question.id %}" method="post">
{% csrf_token %}
{% for choice in question.choice_set.all %}
<input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}" />
<label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br />
{% endfor %}
<input type="submit" value="Vote" />
</form>

polls/templates/polls/results.html：

<h1>{{ question.question_text }}</h1>
<ul>
{% for choice in question.choice_set.all %}
<li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
{% endfor %}
</ul>
<a href="{% url 'polls:detail' question.id %}">Vote again?</a>
polls/templates/polls/index.html:
{% if latest_question_list %}
<ul>
{% for question in latest_question_list %}
<li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>
{% endfor %}
</ul>
{% else %}
<p>No polls are available.</p>
{% endif %}

我的网站/设置.py

"""
Django settings for mysite3 project.
Generated by 'django-admin startproject' using Django 2.0.
For more information on this file, see
https://docs.djangoproject.com/en/2.0/topics/settings/
For the full list of settings and their values, see
https://docs.djangoproject.com/en/2.0/ref/settings/
"""
import os
# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/2.0/howto/deployment/checklist/
# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '*8a@se$l_8v%(-xyz=!!=jgvyjyn611zqw(dqroejvkk^o9%co'
# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True
ALLOWED_HOSTS = []

# Application definition
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'polls.apps.PollsConfig',
]
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',
]
ROOT_URLCONF = 'mysite3.urls'
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': [],
'APP_DIRS': True,
'OPTIONS': {
'context_processors': [
'django.template.context_processors.debug',
'django.template.context_processors.request',
'django.contrib.auth.context_processors.auth',
'django.contrib.messages.context_processors.messages',
],
},
},
]
WSGI_APPLICATION = 'mysite3.wsgi.application'

# Database
# https://docs.djangoproject.com/en/2.0/ref/settings/#databases
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
}
}

# Password validation
# https://docs.djangoproject.com/en/2.0/ref/settings/#auth-password-validators
AUTH_PASSWORD_VALIDATORS = [
{
'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
},
{
'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
},
{
'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
},
{
'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
},
]

# Internationalization
# https://docs.djangoproject.com/en/2.0/topics/i18n/
LANGUAGE_CODE = 'en-us'
TIME_ZONE = 'UTC'
USE_I18N = True
USE_L10N = True
USE_TZ = True

# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/2.0/howto/static-files/
STATIC_URL = '/static/'

Answer 1

这是引发错误的行：

selected_choice = Question.choice_set.get(pk=request.POST['choice'])

基本上，您需要在 Question 模型的实例上调用choice_set，而不是在模型本身上调用。

所以这样的事情可能会起作用：

question = Question.objects.get(pk=question_id)
selected_choice = question.choice_set.get(pk=request.POST['choice'])