django 39 rest framework filter by url parameter

get request to http://127.0.0.1:8000/api/album_list/?author=chuanshuo&data_length=2

server returns 2 of chuanshuo's posts

#music/api/apiview

from music.models import Album
from music.api.serializers import MusicSerializer
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from django.http import Http404
from django.contrib.auth.models import User
from django.shortcuts import get_object_or_404

class AlbumList(APIView):
    def get(self, request, format=None):
        username = request.GET.get('author')
        data_length = request.GET.get('data_length')

        #filter by author
        if username==None:
            albums = Album.objects.all()
        else:
            author_id = get_object_or_404(User, username=username).pk
            albums = Album.objects.filter(author=author_id).order_by('-date_posted')

        #filter by data length
        if data_length!=None:
            try:
                int(data_length)
            except ValueError:
                return Response('data length is invvalid', status=status.HTTP_406_NOT_ACCEPTABLE)
            else:
                albums = albums[:int(data_length)]

        serializer = MusicSerializer(albums, many=True)
        return Response(serializer.data)

    def post(self, request, format=None):
        serializer = MusicSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

class AlbumDetail(APIView):

    def get_object(self, pk):
        try:
            return Album.objects.get(pk=pk)
        except Album.DoesNotExist:
            raise Http404

    def get(self, request, pk, format=None):
        album = self.get_object(pk)
        serializer = MusicSerializer(album)
        return Response(serializer.data)

    def put(self, request, pk, format=None):
        album = self.get_object(pk)

        #only owner can edit
        if album.author != request.user:
            return Response({"detail": "You do not have permission to perform this action."},
                            status= status.HTTP_403_FORBIDDEN)

        serializer = MusicSerializer(album, data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def delete(self, request, pk, format=None):
        album = self.get_object(pk)

        # only owner can delete
        if album.author != request.user:
            return Response({"detail": "You do not have permission to perform this action."},
                            status=status.HTTP_403_FORBIDDEN)

        album.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

reference:
https://pypi.org/project/django-filter/
https://www.django-rest-framework.org/api-guide/status-codes/
https://stackoverflow.com/questions/25928990/catching-any-doesnotexist-error
https://chuanshuoge2.blogspot.com/2019/05/django-38-rest-framework-authentication.html