Django rest framework: omit dict where field is empty - django

Question

I'm building a rest API for a media library.
Here are some of my python code, I have simplify them a bit, so only the necessary code is included, to have a better overview about the current problem.
models.py:
class MediaSeries(models.Model):
name = models.CharField(max_length=200)
description = models.TextField(blank=True)
class MediaSeriesEntries(models.Model):
serie = models.ForeignKey(MediaSeries, related_name='series',
db_column='seriesID', null=True,
on_delete=models.SET_NULL)
file = models.ForeignKey(MediaFiles, related_name='serie_set',
db_column='fileID', null=True,
on_delete=models.SET_NULL)
class MediaFiles(models.Model):
youtube = models.CharField(max_length=300, blank=True)
name = models.CharField(max_length=300)
screeningPause = models.BooleanField(default=0)
duration = models.BigIntegerField(default=0)
creatingDate = models.DateTimeField(default=now)
class Library(models.Model):
media = models.ForeignKey(MediaFiles, related_name='library_set',
db_column='fileID', null=True,
on_delete=models.SET_NULL)
visits = models.IntegerField(default=0)
likes = models.IntegerField(default=0)
views.py:
class LibraryMediaFilter(filters.FilterSet):
class Meta:
model = Library
fields = ['media__name', 'media__duration',
'media__youtube', 'media__creatingDate']
class LibraryMediaViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows the library to be viewed.
Example ordering:
http://127.0.0.1:8000/api/library-media/?ordering=media__creatingDate
"""
queryset = Library.objects.all() \
.exclude(media__youtube="").exclude(media__screeningPause=True)
serializer_class = LibraryMediaSerializer
pagination_class = LibraryResultsSetPagination
filter_backends = (filters.DjangoFilterBackend, OrderingFilter)
filterset_class = LibraryMediaFilter
ordering_fields = ['media__serie_set__serie__name', 'media__name',
'media__creatingDate', 'visits', 'likes']
serializers.py:
class LibraryMediaSerializer(serializers.ModelSerializer):
name = serializers.CharField(source='media.name', read_only=True)
duration = serializers.IntegerField(source='media.duration',
read_only=True)
youtube = serializers.CharField(source='media.youtube', read_only=True)
creatingDate = serializers.DateTimeField(source='media.creatingDate',
read_only=True)
serie_set = SeriesEntriesSerializer(source='media.serie_set',
read_only=True, many=True)
class Meta:
model = Library
fields = ('visits', 'likes', 'name', 'duration', 'youtube',
'creatingDate', 'serie_set')
When I call now the api with http://example.org/api/library-media/ I get this result:
{
"visits": 0,
"likes": 0,
"name": "example movie",
"duration": 9505000,
"youtube": "https://youtu.be/34345",
"creatingDate": "2013-01-01T01:00:00+01:00",
"serie_set": []
},
{
"visits": 0,
"likes": 0,
"name": "example serie",
"duration": 3436000,
"youtube": "https://youtu.be/z0c4rLCcyVE",
"creatingDate": "2013-01-01T01:00:00+01:00",
"serie_set": [
{
"name": "Das große Ganze",
"description": ""
}
]
},
Now I would like to filter against empty and not empty serie_set, with something like:
http://example.org/api/library-media/media__serie_set__isempty=true
or:
http://example.org/api/library-media/media__serie_set__isempty=false