c3lf-system-3/core/inventory/shared_serializers.py

from rest_framework import serializers

from inventory.models import Event, Item


class BasicItemSerializer(serializers.ModelSerializer):
    cid = serializers.SerializerMethodField()
    box = serializers.SerializerMethodField()
    file = serializers.SerializerMethodField()
    returned = serializers.SerializerMethodField(required=False)
    event = serializers.SlugRelatedField(slug_field='slug', queryset=Event.objects.all(),
                                         allow_null=True, required=False)

    class Meta:
        model = Item
        fields = ['cid', 'box', 'id', 'description', 'file', 'returned', 'event']
        read_only_fields = ['id']

    def get_cid(self, instance):
        return instance.container.id if instance.container else None

    def get_box(self, instance):
        return instance.container.name if instance.container else None

    def get_file(self, instance):
        if len(instance.files.all()) > 0:
            return sorted(instance.files.all(), key=lambda x: x.created_at, reverse=True)[0].hash
        return None

    def get_returned(self, instance):
        return instance.returned_at is not None