Specify the parameter of query string as "lookup_field"

[k***@gmail.com]

Hi,

I'd like to use the parameter of query string as the lookup_field of
RetrieveAPIView.

As described, it's possible to specify the captured parameter,

$ cat users/urls.py
...
url(r'^user/(?P<user_id>.+)/$', views MyUser.as_view()),
...

$ cat users/views.py
class MyUser(RetrieveAPIView):
serializer_class = UserSerializer

queryset = User.objects.all()
lookup_field = "user_id"

$ curl http://localhost:8000/user/10/
200


However, the following case doesn't work.

$ cat users/urls.py
...
url(r'^user/$', views MyUser2.as_view()),
...

$ cat users/views.py
class MyUser2(RetrieveAPIView):
serializer_class = UserSerializer

queryset = User.objects.all()
lookup_field = "email"

$ curl http://localhost:8000/user/?email='***@example.com'

AssertionError: Expected view MyUser2 to be called with a URL keyword
argument named "email". Fix your URL conf, or set the `.lookup_field`
attribute on the view correctly.
[24/May/2018 16:23:28] "GET /users/ HTTP/1.1" 500 18819


Is there a way to do it?

I read "get_object()" in generics.py. It seems to look up from "kwargs".
https://github.com/encode/django-rest-framework/blob/cdb8a3c3c86bbb74f17f8880c52000602b015ed4/rest_framework/generics.py#L90-L95

Should I use APIView instead of RetrieveAPIView and implement "get()"
method by myself?
Or, can I modify "get_object()" to look up from GET query and send PR?

Thanks,
Teppei