@api_view(['GET'])
@authentication_classes((BasicAuthentication,))
@permission_classes((IsAuthenticated,))
def get_key(request):
    username = request.user.username
    enc = encode(key, username)
    return Response({'API_key': enc, 'username': username}, status=status.HTTP_200_OK)

@api_view(['GET'])
def get_data(request):
    user = request.user
    API_key = request.META.get('Authorization') # the value is null
    return Response({'API_key': API_key})

headers = {'Authorization': 'yNd5vdL4f6d4f6dfsdF29DPh9vUtg=='}
r = requests.get('http://localhost:8000/api/getdata', headers=headers)

API_key = request.META.get('HTTP_AUTHORIZATION')