Facing use while declare custom Lookup field

[he-kishor]

I am facing an issue while using lookup_field. I declared it as email, but when I request the method, it shows "not found". The email field has a unique constraint. However, when I use pk and search using pk, it shows me the user data.

views code is given below
class UserViewSetTesting(viewsets.ViewSet):
"""A simple ViewSet for listing or retreiving users"""
lookup_field = 'email'
def list(self,request):
queryset=User.objects.all()
serializer=UserSerializers(queryset, many=True)
return Response(serializer.data)

def retrieve(self,request,email=None):
    queryset=User.objects.all()
    user=get_object_or_404(queryset,email=email)
    serializer=UserSerializers(user)
    return Response(serializer.data)
the get method URL is 

http://127.0.0.1:8000/api/usertesting/[email protected]
shows me not found while the email Id is correct