Question

我正在创建一个django应用程序。据我所知，一切都在views.py中但是当我运行服务器时它会生成一个错误local variable 'state' referenced before assignment

我在上面的视图中创建了context_dict变量，但它也产生了错误。

views.py

from django.shortcuts import render
from .models import States,Colleges

def index(request):
    all_states = States.objects.all()
    context_dict = {'all_states':all_states}
    return render(request,'practise_app/index.html',context_dict)

def college(request,state_slug):

    try:
        state = States.objects.get(slug = state_slug)
        colleges = Colleges.objects.filter(state = state)
        context_dict = {'state':state,'colleges':colleges}

    except States.DoesNotExist:
        pass

    return render(request,'practise_app/colleges.html',context_dict)

TRACEBACK：

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8000/madhya-pradesh/

Django Version: 1.8
Python Version: 3.5.1
Installed Applications:
('django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'practise_app')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware')


Traceback:
File "C:\Users\sahib navlani\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\handlers\base.py" in get_response
  132.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "D:\practise_project\practise_app\views.py" in college
  19.     return render(request,'practise_app/colleges.html',context_dict)

Exception Type: UnboundLocalError at /madhya-pradesh/
Exception Value: local variable 'context_dict' referenced before assignment

Answer 1

很明显，您的代码转到except块，但context_dict仅在try块中定义，因此当您在render函数中使用它时，它没有定义。最快的解决方法是将context_dict定义为函数开头的空字典，以便在返回时始终存在。

在赋值之前引用的局部变量context_dict

1 个答案: