Question

我收到以下错误

错误：反向placeinterest参数('',)且未找到关键字参数{}。 1种模式尝试过：

[u'polls/(?P<section_id>[0-9]+)/placeinterest/$']

我通过Django示例处理了一个轮询应用程序，现在我正在尝试创建一个适应我已有的类注册应用程序。错误指向第5行：

<h1>{{ section.class_name }}</h1>

{% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}

<form action="{% url 'polls:placeinterest' section.id %}" method="post">
{% csrf_token %}
<input type="radio" name="incr" id="incr" value="incr" />
<label for="incr"></label><br />
<input type="submit" value="Placeinterest" />
</form>

但我认为问题出在我的placeinterest函数中：

def placeinterest(request, section_id):
    section = get_object_or_404(Section, pk=section_id)
    try:
        selected_choice = section.num_interested
    except (KeyError, Section.num_interested.DoesNotExist):
        # Redisplay the question voting form.
        return render(request, 'polls/detail.html', {
            'section': section,
            'error_message': "You didn't select a choice.",
        })
    else:
        section.num_interested += 1
        section.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=(section.id,)))

如果我的Section类看起来像这样，我不确定我的POST调用应该是什么：

class Section(models.Model):
    class_name = models.CharField(max_length=200)
    num_interested = models.IntegerField(default=0)
    pub_date = models.DateTimeField('date published')
    def __str__(self):
        return self.class_name
    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(minutes=3)
    def some_interested(self):
        if self.num_interested > 0:
            return "There is currently interest in this class"
        else:
            return "There is currently no interest in this class"

结果部分在我的浏览器中显示正常，这是urls.py的好措施：

from django.conf.urls import url

from . import views

app_name = 'polls'
urlpatterns = [
    url(r'^$', views.IndexView.as_view(), name='index'),
    url(r'^(?P<pk>[0-9]+)/$', views.DetailView.as_view(), name='detail'),
    url(r'^(?P<pk>[0-9]+)/results/$', views.ResultsView.as_view(), name='results'),
    url(r'^(?P<section_id>[0-9]+)/placeinterest/$', views.placeinterest, name='placeinterest'),
]

编辑：添加示例中的原始代码，希望可以帮助别人看到我出错的地方：

网址：

from django.conf.urls import url

from . import views

app_name = 'polls'
urlpatterns = [
    url(r'^$', views.IndexView.as_view(), name='index'),
    url(r'^(?P<pk>[0-9]+)/$', views.DetailView.as_view(), name='detail'),
    url(r'^(?P<pk>[0-9]+)/results/$', views.ResultsView.as_view(), name='results'),
    url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),
]

在views.py中投票功能：

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'])
    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,)))

detail.html，我在进行更改后遇到问题：

<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>

Answer 1

错误与您的观点无关。它明确表示它正在尝试匹配错误中名为placeinterest的URL。它知道URL存在，但参数错误。

它认为您正在尝试将空字符串作为位置参数传递。这意味着在呈现模板时section.id可能是None。它将null值转换为空字符串并将其作为位置参数传递，因此('',)。这是一个元组，其中包含一个空字符串值。

Answer 2

问题在于：

<form action="{% url 'polls:placeinterest' section.id %}" method="post">

Django无法找出url参数，因为它配置错误。使用此：

<form action="{% url 'polls:placeinterest' section_id=section.id %}" method="post">

您还需要确保部分ID有效（请注意您提供的"section"作为上下文。

Django“反向____带参数”......错误

2 个答案: