在Python Shell中創建對象，查詢時無法識別

Question

當前爲我正在做的一些工作創建一個Django站點。以下是相關的代碼塊：

門戶/ device_categories/models.py

from django.db import models 

# Create your models here. 
class Type(models.Model): 
    device_category = models.CharField(max_length=20) 

def __str__(self): 
    return self.device_category 

class Device(models.Model): 
    category = models.ForeignKey(Type, on_delete=models.CASCADE) 
    tms_code = models.CharField(max_length=5) 
    device_name = models.CharField(max_length=30) 
    device_count = models.CharField(max_length=3) 

    def __str__(self): 
     return "Device:" + self.device_name 

門戶/ device_categories/urls.py

from django.conf.urls import url 
from . import views 

urlpatterns = [ 
    url(r'^$', views.index, name='index'), 
    url(r'^(?P<device_type>[A-Za-z]+)/$', views.deviceList, name='deviceList'), 
] 

門戶/ device_categories /視圖。 py

from django.shortcuts import render 
from django.http import HttpResponse 
from .models import Type, Device 
from django.template import loader 

# Create your views here. 
def index(request): 
    return HttpResponse("This is the Device Categories Page") 

def deviceList(request, device_type): 
    all_devices = Device.objects.get(category__device_category=device_type) 
    template = loader.get_template('device_categories/index.html') 
    context = { 
     'all_devices': all_devices, 
    } 
    return render(request, template, context) 

我已經創建了許多設備使用對象：

python manage.py shell 

方法，一些示例性類別包括：風扇，開關模塊。所有類別也被設置爲他們自己的類型類別。現在我有分配粉絲5類對象，但是當我嘗試去網址：

127.0.0.1:8000/device_categories/fans/

我得到錯誤：

Environment: 


Request Method: GET 
Request URL: http://127.0.0.1:8000/device_categories/fans/ 

Django Version: 1.11.4 
Python Version: 3.6.0 
Installed Applications: 
['network_resources.apps.NetworkResourcesConfig', 
'device_categories.apps.DeviceCategoriesConfig', 
'device_inventory.apps.DeviceInventoryConfig', 
'on_call.apps.OnCallConfig', 
'contact_info.apps.ContactInfoConfig', 
'django.contrib.admin', 
'django.contrib.auth', 
'django.contrib.contenttypes', 
'django.contrib.sessions', 
'django.contrib.messages', 
'django.contrib.staticfiles'] 
Installed Middleware: 
['django.middleware.security.SecurityMiddleware', 
'django.contrib.sessions.middleware.SessionMiddleware', 
'django.middleware.common.CommonMiddleware', 
'django.middleware.csrf.CsrfViewMiddleware', 
'django.contrib.auth.middleware.AuthenticationMiddleware', 
'django.contrib.messages.middleware.MessageMiddleware', 
'django.middleware.clickjacking.XFrameOptionsMiddleware'] 



Traceback: 

File "C:\Program Files (x86)\Python36-32\lib\site-packages\django-1.11.4-py3.6.egg\django\core\handlers\exception.py" in inner 
    41.    response = get_response(request) 

File "C:\Program Files (x86)\Python36-32\lib\site-packages\django-1.11.4-py3.6.egg\django\core\handlers\base.py" in _get_response 
    187.     response = self.process_exception_by_middleware(e, request) 

File "C:\Program Files (x86)\Python36-32\lib\site-packages\django-1.11.4-py3.6.egg\django\core\handlers\base.py" in _get_response 
    185.     response = wrapped_callback(request, *callback_args, **callback_kwargs) 

File "C:\users\wskidmor\Django\nocportal\device_categories\views.py" in deviceList 
    11.  all_devices = Device.objects.get(category__device_category=device_type) 

File "C:\Program Files (x86)\Python36-32\lib\site-packages\django-1.11.4-py3.6.egg\django\db\models\manager.py" in manager_method 
    85.     return getattr(self.get_queryset(), name)(*args, **kwargs) 

File "C:\Program Files (x86)\Python36-32\lib\site-packages\django-1.11.4-py3.6.egg\django\db\models\query.py" in get 
    380.     self.model._meta.object_name 

Exception Type: DoesNotExist at /device_categories/fans/ 
Exception Value: Device matching query does not exist. 

我已經驗證了當我進入shell時存在的對象，所以我不知道我在做什麼錯誤。我發現在這裏發佈了類似的問題，但我已經嘗試過這些解決方案，但不幸的是沒有申請。感謝您的幫助

Answer 1

更改這一行的意見吧：

all_devices = Device.objects.get(category__device_category=device_type) 

要：

all_devices = Device.objects.filter(category__device_category=device_type)