DRF：方法GET基于参数返回对象

Question

I am learning Django and am trying to build an endpoint that returns the objects based on a parameter given in the URL.

Currently I have these URLS:

/api/v1/ as root which returns:

GET /api/v1/

HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "device-groups": "http://127.0.0.1:8000/api/v1/device-groups/"
}

/api/v1/device-groups/ which returns all the device groups:

HTTP 200 OK
Allow: GET, POST, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

[
    {
        "device_group_name": "Default",
        "group_uuid": "7465febe-7c46-4420-85a1-73dfe0af812c",
        "color": "4286f4",
        "is_default": true,
        "customer": {
            "customer_name": "Customer1",
            "customer_uuid": "b3eb5d7d-d1a8-4997-a65b-28bed71b7cc6"
        }
    },
    {
        "device_group_name": "Default",
        "group_uuid": "e12d02d0-7916-477e-b318-9680a38617db",
        "color": "4286f4",
        "is_default": true,
        "customer": {
            "customer_name": "Another customer",
            "customer_uuid": "5b5dafab-c311-4f58-80f5-c50d77fcf8a5"
        }
    },
    {
        "device_group_name": "group of customer1",
        "group_uuid": "c72e87b1-e7c8-4dcd-a9c7-4f6a016d7676",
        "color": "#ffffff",
        "is_default": false,
        "customer": {
            "customer_name": "Customer1",
            "customer_uuid": "b3eb5d7d-d1a8-4997-a65b-28bed71b7cc6"
        }
    }
]

I want an endpoint like /api/v1/device-groups/<customer_uuid>/ which returns the device groups that are related to the given customer_uuid.

My serializers.py :

class CustomerSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = Customer
        fields = ('customer_name', 'customer_uuid')


class DeviceGroupSerializer(serializers.HyperlinkedModelSerializer):
    customer = CustomerSerializer(many=False, read_only=True)

    class Meta:
        model = DeviceGroup
        fields = ('device_group_name', 'group_uuid', 'color', 'is_default', 'customer')

My views.py :

class DeviceGroupViewSet(viewsets.ModelViewSet):
    serializer_class = DeviceGroupSerializer
    queryset = DeviceGroup.objects.all()

My urls.py :

router = routers.DefaultRouter()
router.register(r'device-groups', views.DeviceGroupViewSet)


urlpatterns = [
   path('admin/', admin.site.urls),
   path('api/v1/', include(router.urls)),
]

I tried overriding get_queryset like this:

def get_queryset(self):
    customer = self.request.GET['customer']
    queryset = DeviceGroup.objects.filter(customer=customer)
    return queryset

But it results in: AssertionError: basename argument not specified, and could not automatically determine the name from the viewset, as it does not have a .queryset attribute.

What do I need to change to get an /api/v1/device-groups/<customer_uuid>/ endpoint which only shows device groups that are related to the given customer_uuid?

EDIT

Internal Server Error: /api/v1/device-groups/
Traceback (most recent call last):
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\django\utils\datastructures.py", line 77, in __getitem__
list_ = super().__getitem__(key)
KeyError: 'customer'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\django\core\handlers\exception.py", line 34, in inner
response = get_response(request)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\django\core\handlers\base.py", line 126, in _get_response
response = self.process_exception_by_middleware(e, request)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\django\core\handlers\base.py", line 124, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\django\views\decorators\csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\rest_framework\viewsets.py", line 116, in view
return self.dispatch(request, *args, **kwargs)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\rest_framework\views.py", line 495, in dispatch
response = self.handle_exception(exc)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\rest_framework\views.py", line 455, in handle_exception
self.raise_uncaught_exception(exc)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\rest_framework\views.py", line 492, in dispatch
response = handler(request, *args, **kwargs)
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\rest_framework\mixins.py", line 40, in list
queryset = self.filter_queryset(self.get_queryset())
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\app\core\views.py", line 
13, in get_queryset
customer = self.request.GET['customer']
File "C:\Users\Stevy\PycharmProjects\tapartisan-api\env\lib\site- 
packages\django\utils\datastructures.py", line 79, in __getitem__
raise MultiValueDictKeyError(key)
django.utils.datastructures.MultiValueDictKeyError: 'customer'`

Answer 1

Router could not determine basename . You have to define a basename in your router. Like this

router.register(r'device-groups', views.DeviceGroupViewSet, base_name='device-groups')

base_name is actually used to generate names for routes / urls. You can read more about it here .

Answer 2

I am not familiar with DRF but in general in order to get the object based on a parameter you have to:

1) Define your url in such a way to take in mind the customer_uuid you are going to type dynamically when you want to build your endpoint So, with the help of regex you have to build something like:

url(r'^/api/v1/device-groups/(?P<customer_uuid>\d+)/$', views.your_view, name='your_view')

The regex \\d+ will match an integer of arbitrary size. This integer will be used to retrieve the Customer from the database. Now observe that I wrote the regex as (?P\\d+), this is telling Django to capture the value into a keyword argument named customer_uuid.

2) Define your view function

from django.shortcuts import render, get_object_or_404
from .models import Customer

def your_view(request, customer_uuid):
    customer = get_object_or_404(Customer, pk=customer_uuid)
    return render(request, 'customer.html', {'customer': customer})

Hope it helps

Answer 3

You should get what you want if you define a different lookup_field in the view like:

class DeviceGroupViewSet(viewsets.ModelViewSet):
    serializer_class = DeviceGroupSerializer
    queryset = DeviceGroup.objects.all()
    lookup_field = 'customer_uuid'

Or maybe you'dl like to take a look to this documentation to consider a different approach.