Move apps in main directory

Signed-off-by: Emmy D'Anello <emmy.danello@animath.fr>

registration/api/serializers.py

@@ -0,0 +1,40 @@
+# Copyright (C) 2020 by Animath
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from rest_framework import serializers
+from rest_polymorphic.serializers import PolymorphicSerializer
+
+from ..models import CoachRegistration, ParticipantRegistration, \
+    StudentRegistration, VolunteerRegistration
+
+
+class CoachSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = CoachRegistration
+        fields = '__all__'
+
+
+class ParticipantSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = ParticipantRegistration
+        fields = '__all__'
+
+
+class StudentSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = StudentRegistration
+        fields = '__all__'
+
+
+class VolunteerSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = VolunteerRegistration
+        fields = '__all__'
+
+
+class RegistrationSerializer(PolymorphicSerializer):
+    model_serializer_mapping = {
+        CoachRegistration: CoachSerializer,
+        StudentRegistration: StudentSerializer,
+        VolunteerRegistration: VolunteerSerializer,
+    }