old_contents: import requests
  from django.conf import settings
  from rest_framework import serializers
  from rest_framework.validators import UniqueTogetherValidator
  from server.api.serializers.chapters import ChapterSerializer
  from .riders import RiderSerializer
  from server.core.models.rides import Ride, RideRiders
  
  
  class RideSerializer(serializers.ModelSerializer):
      chapter = ChapterSerializer()
      riders = RiderSerializer(source='registered_riders', many=True, read_only=True)
  
      class Meta:
          model = Ride
          fields = ('id', 'name', 'slug', 'description_html', 'start_location', 'end_location', 'start_date', 'end_date',
                    'chapter', 'rider_capacity', 'riders', 'spaces_left', 'price', 'full_cost', 'currency', 'is_over',
                    'fundraising_total', 'fundraising_target')
  
  
  class RideRiderSerializer(serializers.ModelSerializer):
      user = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault())
  
      class Meta:
          model = RideRiders
          fields = ('ride', 'user', 'signup_date', 'signup_expires', 'status', 'paid', 'expired', 'payload')
          validators = [
              UniqueTogetherValidator(
                  queryset=RideRiders.objects.all(),
                  fields=('user', 'ride'),
                  message='You have already registered for this ride.'
              )
          ]
new_contents: import requests
  from django.conf import settings
  from rest_framework import serializers
  from rest_framework.validators import UniqueTogetherValidator
  from server.api.serializers.chapters import ChapterSerializer
  from .riders import RiderSerializer
  from server.core.models.rides import Ride, RideRiders
  
  
  class RideSerializer(serializers.ModelSerializer):
      chapter = ChapterSerializer()
      riders = RiderSerializer(source='registered_riders', many=True, read_only=True)
  
      class Meta:
          model = Ride
          fields = ('id', 'name', 'slug', 'description_html', 'start_location', 'end_location', 'start_date', 'end_date',
                    'chapter', 'rider_capacity', 'riders', 'spaces_left', 'price', 'full_cost', 'currency', 'is_over',
                    'fundraising_total', 'fundraising_target')
  
  
  class RideRiderSerializer(serializers.ModelSerializer):
      user = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault())
  
      class Meta:
          model = RideRiders
          fields = ('id', 'ride', 'user', 'signup_date', 'signup_expires', 'status', 'paid', 'expired', 'payload')
          validators = [
              UniqueTogetherValidator(
                  queryset=RideRiders.objects.all(),
                  fields=('user', 'ride'),
                  message='You have already registered for this ride.'
              )
          ]
subject: Send RideRegistration id through with api response