在 Python Shell 中创建对象，查询时无法识别

Question

目前正在为我正在做的一些工作创建一个 Django 站点。以下是相关的代码块：

portal/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

portal/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'),
]

portal/device_categories/views.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)

我使用以下方法创建了许多 设备对象 ：

python manage.py shell

方法，一些示例类别是：风扇、开关、模块。所有类别也已设置为自己的类型Class。现在我有 5 个对象，我分配了一个粉丝类别，但是当我尝试去 url:

127.0.0.1:8000/device_categories/fans/

我遇到错误：

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.

当我进入 shell 时，我已经验证了这些对象存在，所以我不确定我做错了什么。我在这里发现了类似的问题，但我已经尝试了这些解决方案，但不幸的是它们不适用。感谢您的帮助

Answer 1

在您的视图中更改此行：

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

收件人：

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

在 Python Shell 中创建对象，查询时无法识别

Created Object in Python Shell, not recognized when queried

django

error-handling

invalid-object-name