AdventureLog/backend/server/worldtravel/serializers.py

import os
from .models import Country, Region, VisitedRegion
from rest_framework import serializers

class CountrySerializer(serializers.ModelSerializer):
    def get_public_url(self, obj):
        return os.environ.get('PUBLIC_URL', 'http://127.0.0.1:8000').rstrip('/').replace("'", "")

    flag_url = serializers.SerializerMethodField()
    num_regions = serializers.SerializerMethodField()
    num_visits = serializers.SerializerMethodField()

    def get_flag_url(self, obj):
        public_url = self.get_public_url(obj)
        return public_url + '/media/' + 'flags/' + obj.country_code.lower() + '.png'
    
    def get_num_regions(self, obj):
        # get the number of regions in the country
        return Region.objects.filter(country=obj).count()
    
    def get_num_visits(self, obj):
        request = self.context.get('request')
        if request and hasattr(request, 'user'):
            return VisitedRegion.objects.filter(region__country=obj, user_id=request.user).count()
        return 0

    class Meta:
        model = Country
        fields = '__all__'
        read_only_fields = ['id', 'name', 'country_code', 'subregion', 'flag_url', 'num_regions', 'num_visits']


class RegionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Region
        fields = '__all__'
        read_only_fields = ['id', 'name', 'country', 'longitude', 'latitude']

class VisitedRegionSerializer(serializers.ModelSerializer):
    longitude = serializers.DecimalField(source='region.longitude', max_digits=9, decimal_places=6, read_only=True)
    latitude = serializers.DecimalField(source='region.latitude', max_digits=9, decimal_places=6, read_only=True)
    name = serializers.CharField(source='region.name', read_only=True)

    class Meta:
        model = VisitedRegion
        fields = ['id', 'user_id', 'region', 'longitude', 'latitude', 'name']
        read_only_fields = ['user_id', 'id', 'longitude', 'latitude', 'name']