如何修复 Django 表中删除按钮的 NoReverseMatch 错误

Question

Python 版本 3.7.7 和 Django 版本 2.2.3。 Github 上的代码 https://github.com/jcwill415/Stock_Market_Web_App

我想在表格的最后一列中添加一个删除按钮。当代码在表之外时，它可以从表中删除一个条目。但是当代码在表格内时，我收到一个 NoReverseMatch 错误，上面写着：

  NoReverseMatch at /add_stock.html 
  Reverse for 'delete' with arguments '('',)' not found. 1 pattern(s) tried: ['delete/(?P<stock_id>[^/]+)$']

Request Method: GET
Request URL:    http://localhost:8000/add_stock.html
Django Version: 2.2.3
Exception Type: NoReverseMatch
Exception Value:    
Reverse for 'delete' with arguments '('',)' not found. 1 pattern(s) tried: ['delete/(?P<stock_id>[^/]+)$']
Exception Location: C:\djangostock\venv\lib\site-packages\django\urls\resolvers.py in _reverse_with_prefix, line 668
Python Executable:  C:\djangostock\venv\Scripts\python.exe
Python Version: 3.7.7
Python Path:    
['C:\\Users\\JCW\\Desktop\\Stock_Market_Web_App-master\\stock',
 'C:\\Users\\JCW\\AppData\\Local\\Programs\\Python\\Python37-32\\python37.zip',
 'C:\\Users\\JCW\\AppData\\Local\\Programs\\Python\\Python37-32\\Lib',
 'C:\\Users\\JCW\\AppData\\Local\\Programs\\Python\\Python37-32\\DLLs',
 'C:\\Program Files\\Python37',
 'C:\\djangostock\\venv',
 'C:\\djangostock\\venv\\lib\\site-packages']

add_stock.html

<table class="table table-striped table-hover">

  <thead class="thead-dark">
    <tr>
      <th scope="col">TICKER</th>
      <th scope="col">COMPANY</th>
      <th scope="col">STK PRICE</th>
      <th scope="col">PREV CLOSE</th>
      <th scope="col">MARKET CAP</th>
      <th scope="col">VOLUME</th>
      <th scope="col">YTD CHG</th>
      <th scope="col">52 WK HIGH</th>
      <th scope="col">52 WK LOW</th>
      <th scope="col">REMOVE STK</th>
    </tr>
  </thead>
  <tbody>
{% if ticker %}
      
            {% for list_item in output %}
                <tr>
                    <th scope="row">{{ list_item.symbol }}</th>
                    <td>{{ list_item.companyName }}</td>
                    <td>${{ list_item.latestPrice }}</td/>
                    <td>${{ list_item.previousClose }}</td>
                    <td>${{ list_item.marketCap }}</td>
                    <td>{{ list_item.latestVolume }}</td>
                    <td>{{ list_item.ytdChange }}</td>
                    <td>${{ list_item.week52High }}</td>
                    <td>${{ list_item.week52Low }}</td>
                    <td><a href="{% url 'delete' item.id %}" class="btn btn-outline-danger btn-small">Delete {{ item }}</a></br></td>          
        </tr>
        
            {% endfor %}
        
  </tbody>
</table>
{% endif %}

{% for item in ticker %}
    <a href="{% url 'delete' item.id %}" class="btn btn-outline-danger btn-small">Delete {{ item }}</a> &nbsp;
{% endfor %}

views.py

def delete(request, stock_id):
    item = Stock.objects.get(pk=stock_id) # call database by primary key for id #
    item.delete()
    messages.success(request, ("Stock Has Been Deleted From Portfolio!"))
    return redirect('add_stock')

urls.py

from django.urls import path
from . import views

urlpatterns = [
    path('', views.home, name="home"),
    path('about.html', views.about, name="about"),
    path('add_stock.html', views.add_stock, name="add_stock"),
    path('delete/<stock_id>', views.delete, name="delete"),
    path('news.html', views.news, name="news"),
    
]

我的尝试 我尝试过使用 for 循环：

{% for item in ticker %}
   <td><a href="{% url 'delete' item.id %}" class="btn btn-outline-danger btn-small">Delete {{ item }}</a></td>
{% endfor %}

但它会循环遍历所有代码，因此每行的表格中的所有条目都有删除按钮。如果我不使用 for 循环，我会收到 NoReverseMatch 错误。我知道有办法解决这个问题，但我一直在努力并寻找了两个多月。

我也尝试了一个 while 循环，但无法让它工作。我尝试将删除表单添加到 add_stock.html 文件中，并在 views.py 文件中添加相应的请求。

我尝试过的链接，但仍然无法解决：

• How to fix Django "NoReverseMatch" Error
• What is a NoReverseMatch error, and how do I fix it?
• NoReverseMatch: Reverse for 'deleted' with no arguments not found. - Django
• how to add delete button in each row of my table?

ments-not-found-django

Answer 1

您在 2 个不同的地方使用 delete。首先，您引用了错误的项目：

{% for list_item in output %}
   ...
   {% url 'delete' item.id %} 

应该是

{% url 'delete' list_item.id %}

第二个是正确的：

{% for item in ticker %}
   <a href="{% url 'delete' item.id %}"

另外，delete 在很多情况下都是保留字。我不认为这里是这种情况，但仍然是一个坏习惯。到处换成delete_stock：

<a href="{% url 'delete_stock' list_item.id %}" ...>

def delete_stock(request, stock_id=None):

path('delete_stock/<stock_id>', views.delete_stock, name="delete_stock"),

stock_id 是整数还是字符串？要找出答案，请在 add_stock() 中的循环内打印：

api = json.loads(api_request.content)
print(api)
output.append(api)

另外，股票 ID 会在 url 中以字符串的形式出现，所以如果是整数，请执行以下操作：

item = Stock.objects.get(pk=int(stock_id))

或使用：

path('delete_stock/<int:stock_id>', views.delete_stock, name="delete_stock"),

其他网址是否有效？

奖励提示：

您的网址中无需包含.html。这看起来很陈旧。更好的形式是：

urlpatterns = [
    path('', views.home, name="home"),
    path('about', views.about, name="about"),
    path('add_stock', views.add_stock, name="add_stock"),
    path('delete_stock/<int:stock_id>', views.delete_stock, name="delete_stock"),
    path('news', views.news, name="news"),
    
]