NoReverseMatch at / 模板渲染期间出错
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【中文标题】NoReverseMatch at / 模板渲染期间出错【英文标题】：NoReverseMatch at / Error during template rendering 【发布时间】：2020-06-08 21:56:33 【问题描述】：当我打开http://127.0.0.1:8000/ 即home.html 时，我得到：
NoReverseMatch at / 和 Reverse for 'exam-detail' with arguments '('',)' 未找到。尝试了 1 种模式：['exam/(?P[^/]+)$']
我认为错误是由于urls.py 中的<str:pk> 造成的。
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：
subject = models.TextField(primary_key = True, unique = True)
def __str__(self):
return self.subject
home.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
% 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
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
【问题讨论】：
网址exam-detail 未找到。请将此 URL 添加到 urls.py 中，或者如果这无效，请检查进行此调用的代码
请在下面的 url 中尝试，看看它是否能解决您的问题。 path("你错过了 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>
【讨论】：
我试过这个。仍然得到同样的错误。 NoReverseMatch at / Reverse for 'exam-detail' with arguments '('',)' 未找到。尝试了 1 种模式：['exam/(?P在 python manage.py shell
from my_app_name.models import Exam
exam = Exam()
exam.subject = ""
exam.save()
我已经执行了这些行。我还为“google”、“english”等主题创建了考试。
现在Exam.objects.all() 回归
<QuerySet [<Exam: google>, <Exam: english>, <Exam: >]>
问题是由于有一个长度为零的字符串作为考试对象之一的主题。现在我使用Exam.objects.get(subject="").delete() 删除了该考试。问题解决了。
% url 'map:exam-detail' exam.subject %
或
% url 'map:exam-detail' exam %
或
% url 'map:exam-detail' exam.pk %
所有这些现在都在工作，因为所有这些都在返回主题。但是% url 'map:exam-detail' exam.id % 行不通。因为我在Exam model中将subject设为primary_key，所以Exam model没有属性id（默认添加的时候没有提到primary_key）。
思考为什么它接受空字符串作为主题，虽然我已经将它定义为primary_key。 然后我想了解 django.db.models.TextField 并键入帮助（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)
现在尝试了验证器... 后续问题link
谢谢大家 穆尼卡
【讨论】：
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