python-tdd/src/apps/api/serializers.py

from rest_framework import serializers

from apps.dashboard.models import Item, List
from apps.lyric.models import User


class ItemSerializer(serializers.ModelSerializer):
    text = serializers.CharField()

    def validate_text(self, value):
        list_ = self.context["list"]
        if list_.item_set.filter(text=value).exists():
            raise serializers.ValidationError("duplicate")
        return value

    class Meta:
        model = Item
        fields = ["id", "text"]

class ListSerializer(serializers.ModelSerializer):
    name = serializers.ReadOnlyField()
    url = serializers.CharField(source="get_absolute_url", read_only=True)
    items = ItemSerializer(many=True, read_only=True, source="item_set")

    class Meta:
        model = List
        fields = ["id", "name", "url", "items"]

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ["id", "username"]