blechreiz-website/eventplanner/serializers.py

from rest_framework import serializers
from .models import EventParticipation, Event


class ParticipationSerializer(serializers.ModelSerializer):
    event = serializers.PrimaryKeyRelatedField(many=False, read_only=False, queryset=Event.objects.all())
    user = serializers.Field(source='get_username')
    status = serializers.CharField(source='status', required=False)

    def get_identity(self, data):
        """  This hook is required for bulk update.  """
        try:
            return data.get('event', None), data.get('user')
        except AttributeError:
            return None

    class Meta:
        model = EventParticipation
        fields = ('event', 'user', 'status', 'comment')