为什么在尝试访问HttpRequest.POST ['choice']值时出现TypeError？如何解决此错误？

Question

我最近一直在学习django教程，但遇到了麻烦。使用post方法提交表单后，我尝试使用.get（）方法获取selected_choice模型对象，但出现TypeError：无法解压缩不可迭代的ModelBase对象错误。

这里是视图

from django.shortcuts import render, get_object_or_404

from django.http import HttpResponseRedirect
from django.urls import reverse
from .models import Question, Choice

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(Question, pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'polls/detail.html', {'question': question, 'error_message': 'Please select a choice and vote'})
    else:
        selected_choice.no_of_votes += 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:result', args=(question.id,)))

def result(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/result.html', {'question': question})

这里是模板

1. detail.html

   
   {% block content_main %}
   
   <h2>{{question.question_text}}</h2>
   {% if error_message %} <strong>{{error_message}}</strong><br><br> {% 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}}" style="margin-left: 20px;">
       <label for="choice{{forloop.counter}}" style="font-size: 20px;">{{choice.choice_text}}</label><br><br>
   {% endfor %} <br>
       <input type="submit" value="vote" style="margin-left: 30px; font-size: 20px;">
   </form>
   
   {% endblock %}
   

2. result.html

{% block content_main %}
<h2>{{question.question_text}}</h2>
{% for choice in question.choice_set.all %}
    <ul>
        <li>{{choice.choice_text}} -- {{choice.no_of_votes}} vote{{choice.no_of_votes|plural}}</li>
    </ul>
{% endfor %}
<a href="{% url 'polls:detail' question.id %}}">Vote again?</a>
{% endblock %}

并且我收到以下错误消息

/ polls / 1 / vote处的TypeError无法解压缩不可迭代的ModelBase对象请求方法：POST请求URL：http://127.0.0.1:8000/polls/1/voteDjango版本：2.2.6异常类型：TypeError异常值：无法解包不可迭代的ModelBase对象异常位置：C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ sql \ query.py在build_filter中，第1187行Python可执行文件：C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ Scripts \ python.exePython版本：3.7.4 Python路径：['C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ mysite'，'C：\ Users \ Neeyat \ AppData \ Local \ Programs \ Python \ Python37 \ python37.zip'，'C：\ Users \ Neeyat \ AppData \ Local \ Programs \ Python \ Python37 \ DLLs'，'C：\ Users \ Neeyat \ AppData \ Local \ Programs \ Python \ Python37 \ lib'，'C：\ Users \ Neeyat \ AppData \ Local \ Programs \ Python \ Python37'，'C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv'，'C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages'，'C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ setuptools-40.8.0-py3.7.egg'，'C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ pip-19.0.3-py3.7.egg']服务器时间：2019年11月13日星期三19:22:30 +0000

在终端，

[[14 / Nov / 2019 00:52:14]“ GET / HTTP / 1.1” 404 2027不找到：/favicon.ico [14 / Nov / 2019 00:52:16]“ GET /favicon.ico HTTP / 1.1”404 2078 [14 / Nov / 2019 00:52:24]“ GET / polls / HTTP / 1.1” 200447[14 / Nov / 2019 00:52:27]“ GET / polls / 1 / HTTP / 1.1” 200 1145内部服务器错误：/ polls / 1 / vote追溯（最近一次呼叫最近）：文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ core \ handlers \ exception.py”，第34行，在内部response = get_response（request）File“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ core \ handlers \ base.py”，第115行，在_get_response中响应= self.process_exception_by_middleware（e，请求）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ core \ handlers \ base.py”，_get_response中的第113行响应= wraped_callback（请求，* callback_args，** callback_kwargs）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ mysite \ polls \ views.py”，第28行，已投票selected_choice = question.choice_set.get（Question，pk = request.POST ['choice']）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ manager.py”，第82行，在manager_method中返回getattr（self.get_queryset（），name）（* args，** kwargs）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ query。 py”，399行，进入clone = self.filter（* args，** kwargs）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ query.py”，过滤器中的第892行返回self._filter_or_exclude（False，* args，** kwargs）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ query.py”，第910行，在_filter_or_exclude中clone.query.add_q（Q（* args，** kwargs））文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ sql \ query.py ”，第1290行，在add_q中子句，_ = self._add_q（q_object，self.used_aliases）文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ sql \ query.py”，_add_q中的第1318行split_subq = split_subq，simple_col = simple_col，文件“ C：\ Users \ Neeyat \ PycharmProjects \ DjangoApps \ Polls \ venv \ lib \ site-packages \ django \ db \ models \ sql \ query.py”，第1187行，在build_filter中arg，value = filter_expr TypeError：无法解压缩不可迭代的ModelBase对象[14 / Nov / 2019 00:52:30]“ POST / polls / 1 / vote HTTP / 1.1”500 102541

我只是从后端Web开发开始，在任何地方都找不到解决方案。这个你能帮我吗。预先谢谢你。

Answer 1

您的views.py只是一个小错误：

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice']) # <-- here
    except (KeyError, Choice.DoesNotExist):
        return render(request, 'polls/detail.html', {'question': question, 'error_message': 'Please select a choice and vote'})
    else:
        selected_choice.no_of_votes += 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:result', args=(question.id,)))

在choice_set中寻找对象时，不再需要指定model本身。