NoReverseMatch at / 模板渲染期间出错
[英]NoReverseMatch at / Error during template rendering
问题描述
When I open http://127.0.0.1:8000/ which is home.html , I am getting:
当我打开http://127.0.0.1:8000/这是home.html ，我得到：
NoReverseMatch at / and Reverse for 'exam-detail' with arguments '('',)' not found.
I think the error is due to <str:pk> in urls.py .我认为该错误是由于urls.py <str:pk>的。
The urls.py file is below: urls.py文件如下：
from . import views
from .views import ExamListView, ExamDetailView
app_name='map'
urlpatterns = [
path("", ExamListView.as_view(), name='map-home'),
path("exam/<str:pk>", ExamDetailView.as_view(), name="exam-detail"),
path("login_student/", views.login_student, name='map-login'),
path("register_student", views.register_student, name='map-register'),
path('add_student/', views.add_student, name='add_student'),
path('front/', views.front, name="front"),
]
models.py :模型.py ：
subject = models.TextField(primary_key = True, unique = True)
def __str__(self):
return self.subject
home.html主页.html
{% extends "map/base.html" %}
{% block content %}
<p>WELCOME HOME</p>
{% for exam in exams %}
<article class="media content-section">
<div class="media-body">
<div class="article-metadata">
<a class="mr-2" href="{% url 'map:exam-detail' exam.subject %}">{{ exam }} </a>
</div>
</div>
</article>
{% endfor %}
{% endblock content %}
base.html基本文件
{% load static %}
<!DOCTYPE html>
<html>
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<link rel="stylesheet" type="text/css" href="{% static 'map/main.css' %}">
{% if title %}
<title>{{ title }}</title>
{% else %}
<title> MAP PAGE </title>
{% endif %}
</head>
<body>
<header class="site-header">
<nav class="navbar navbar-expand-md navbar-dark bg-steel fixed-top">
<div class="container">
<a class="navbar-brand mr-4" href="/">Project M.A.P</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarToggle" aria-controls="navbarToggle" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarToggle">
<div class="navbar-nav mr-auto">
<a class="nav-item nav-link" href="{% url 'map:map-home' %}">Home</a> <!-- no hardcoded links -->
<a class="nav-item nav-link" href="{% url 'map:map-home' %}">About</a>
</div>
<!-- Navbar Right Side -->
<div class="navbar-nav">
{% if user.is_authenticated %}
<a class="nav-item nav-link" href="{% url 'profile' %}">Profile</a>
<a class="nav-item nav-link" href="{% url 'logout' %}">Logout</a>
{% else %}
<a class="nav-item nav-link" href="{% url 'login' %}">Login</a>
<a class="nav-item nav-link" href="{% url 'register' %}">Register</a>
<a class="nav-item nav-link" href="{% url 'map:map-register' %}">Student</a>
{% endif %}
</div>
</div>
</div>
</nav>
</header>
<main role="main" class="container">
<div class="row">
<div class="col-md-8">
{% if messages %}
{% for message in messages %}
<div class="alert alert-{{ message.tags }}">
{{ message }}
</div>
{% endfor %}
{% endif %}
{% block content %}{% endblock %}
</div>
<div class="col-md-4">
<div class="content-section">
<h3>Our Sidebar</h3>
<p class='text-muted'>You can put any information here you'd like.
<ul class="list-group">
<li class="list-group-item list-group-item-light">Latest Posts</li>
<li class="list-group-item list-group-item-light">Announcements</li>
<li class="list-group-item list-group-item-light">Calendars</li>
<li class="list-group-item list-group-item-light">etc</li>
</ul>
</p>
</div>
</div>
</div>
</main>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
</body>
</html>[enter image description here][1]
views.py视图.py
from django.shortcuts import render
from django.http import HttpResponse
from django.http import HttpResponseRedirect
from django.urls import reverse
from . models import Student, Exam
from django.views.generic import ListView, DetailView
def home(request):
context = {
'exams': Exam.objects.all()
}
return render(request, 'map/home.html', context)
class ExamListView(ListView): #class based views
model = Exam
template_name = 'map/home.html' #<app>/<model>_<viewtype>.html
context_object_name = 'exams'
ordering = ['subject'] #['-exam']
class ExamDetailView(DetailView):
model = Exam
2 个解决方案
解决方案1
0 2020-02-25 21:04:40
You missed exam.pk in the home.html Update your code in this manner,您错过了 home.html 中的exam.pk 以这种方式更新您的代码，
<div class="article-metadata">
<a class="mr-2" href="{% url 'map:exam-detail'
exam.pk %}">{{ exam }} </a>
</div>
</div>
解决方案2
0 已采纳 2020-02-26 17:20:35
In python manage.py shell在 python manage.py shell 中
from my_app_name.models import Exam
exam = Exam()
exam.subject = ""
exam.save()
I have executed these lines.我已经执行了这些行。 and I also created exams for subject like "google", "english",..我还为“谷歌”、“英语”等主题创建了考试。
Now Exam.objects.all() returns现在Exam.objects.all()返回
<QuerySet [<Exam: google>, <Exam: english>, <Exam: >]>
The problem is due to having a string of length zero as subject for one of the exam object.问题是由于有一个长度为零的字符串作为其中一个考试对象的主题。 Now I deleted that exam using Exam.objects.get(subject="").delete() .现在我使用Exam.objects.get(subject="").delete()删除了那个考试。 Problem solved.问题解决了。
{% url 'map:exam-detail' exam.subject %}
or或者
{% url 'map:exam-detail' exam %}
or或者
{% url 'map:exam-detail' exam.pk %}
all these are working now because all are returning the subject.所有这些现在都在起作用，因为所有这些都在返回主题。 But {% url 'map:exam-detail' exam.id %} won't work .但是{% url 'map:exam-detail' exam.id %}不起作用。 Because I have made subject as primary_key in the Exam model , so Exam model don't have an attribute id(which is added by default when no primary_key is mentioned).因为我在Exam 模型中将subject作为primary_key ，所以 Exam model 没有属性 id（当没有提到 primary_key 时默认添加）。
thinking about why it has accepted the empty string as a subject, though I have defined it as primary_key.考虑为什么它接受空字符串作为主题，尽管我已将其定义为primary_key。 Then I wanna read about django.db.models.TextField and just keyed help(TextField) and got然后我想阅读关于 django.db.models.TextField 和刚刚键入的 help(TextField) 并得到
TextField(verbose_name=None, name=None, primary_key=False, max_length=None, unique=False, blank=False, null=False, db_index=False, rel=None, default=<class 'django.db.models.fields.NOT_PROVIDED'>, editable=True, serialize=True, unique_for_date=None, unique_for_month=None, unique_for_year=None, choices=None, help_text='', db_column=None, db_tablespace=None, auto_created=False, validators=(), error_messages=None)
Now tried validators ... The follow up problem link现在尝试验证器...后续问题链接
Thank you all Mounika谢谢大家穆尼卡
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