没有主题与给定的查询匹配

Question

enter image description here我正在 Python Crash Course 中学习第 18 章 18.4.3，当我打开 http://localhost:8000/topics/1 时，我遇到了这个问题 - 没有主题与给定的查询匹配。 Django 3.0.7 和 python 3.8

views.py

from django.shortcuts import render,get_object_or_404
from .models import Topic


def index(request):
    return render(request, 'learning_logs/index.html')

def topics(request):
    topics = Topic.objects.order_by('date_added')
    context = {'topics': topics}
    return render(request,'learning_logs/topics.html',context)
def topic(request,topic_id):
    topic = get_object_or_404(Topic,id=topic_id)
    entries = Topic.entry_set.order_by('-date_added')
    context={'topic':topic},{'entries':entries}
    return render(request,'learning_logs/topic.html',context)

urls.py

app_name = 'learning_logs'
urlpatterns = [
    path('admin/', admin.site.urls),
    path('', views.index, name='index'),
    path('topics/',views.topics,name='topics'),
    path('topics/<int:topic_id>/', views.topic, name='topic'),
]

topics.html

{% extends "learning_logs/base.html" %}
{% block content %}
  <p>Topics</p>
  <ul>
      {% for topic in topics %}
        <li>{{ topic }}</li>
        <li>
            <a href="{% url 'topic' topic_id %}">{{ topic }}</a>
        </li>
      {% empty %}
        <li>No topics have been added yet.</li>
      {% endfor %}
  </ul>
{% endblock content %}

topic.html

{% extends 'learning_logs/base.html' %}
{% block header %}
  <h2>{{ topic }}</h2>
{% endblock header %}
{% block content %}
  <p>Entries:</p>
   <ul>
       {% for entry in entries %}
         <li>
             <p>{{ entry.date_added|date:'M d, Y H:i' }}</p>
             <p>{{ entry.text|linebreaks }}</p>
         </li>
      {% empty %}
      <li>There are no entries for this topic yet.</li>
      {% endfor %}
    </ul>

{% endblock content %}

Answer 1

如果你将多个项目传递给模板，你应该在 一个 字典中传递它，所以：

def topic(request,topic_id):
    topic = get_object_or_404(Topic,id=topic_id)
    entries = Topic.entry_set.order_by('-date_added')
    context = {'topic':topic, 'entries':entries}
    return render(request,'learning_logs/topic.html',context)

通过编写 context={'topic':topic},{'entries':entries}，您构建了一个包含两个字典的 2 元组。

在模板中，您还应该使用`topic: 的.id 属性：

&lt;a href="{% url '<b>learning_logs:</b>topic' <b>topic.id</b> %}"&gt;{{ topic }}&lt;/a&gt;

请注意，数据库需要包含具有给定 ID 的 Topic 对象（此处为 1）。如果不是这样，那么页面当然不能呈现不存在的Topic 的详细信息。