Filter related models by authenticated users relation

[NoNameWhatever]

Hi =)

I can't find any documentation about how to only get the related models objects based on the authenticated users relation.

I have three models. One for User, a custom user model with a M2M field to a model called Group. The third model is Post with a text field and a FK field to Group model.

Users have membership to groups with the M2M field. I want them to only be able to post to these groups.

But all groups are in the select option when creating a post. I want to only send back the groups that the user is a member of.

Simplified models:

User
   group = manyToMany(Group)

Group
   name = charfield

Post
   text = textfield
   group = foreignkey(Group)
   by_user = foreignkey(User)

ViewSet like this.

class PostViewSet(viewsets.ModelViewSet):
    """ Post to a group """
    authentication_classes = (TokenAuthentication,)
    permission_classes = (IsAuthenticated,)
    queryset = Post.objects.all()
    serializer_class = serializers.PostSerializer

    def get_queryset(self):
        """ Return objects for the current authenticated user """
        return self.queryset.filter(by_user=self.request.user)

    def perform_create(self, serializer):
        """ Create a Post """
        serializer.save(by_user=self.request.user)

And for serializer, this.

class PostSerializer(serializers.ModelSerializer):
    """ Serializer for Posting to group"""

    class Meta:
        model = Post
        fields = ['id', 'text', 'group']

This setup makes authenticated user to choose every group in the whole db.
I'm trying to do so the groups selectable/sent to frontend is only the groups that the authenticated user are a member of by the M2M field in the user model.

Is it even possible to achieve this?