Use model polymorphism

note/admin.py

@@ -4,7 +4,7 @@
 
 from django.contrib import admin
 
-from .models.notes import Alias, NoteClub, NoteSpecial, NoteUser
+from .models.notes import Alias, Note, NoteClub, NoteSpecial, NoteUser
 from .models.transactions import MembershipTransaction, Transaction, \
     TransactionTemplate
 
@@ -26,8 +26,8 @@ class NoteClubAdmin(admin.ModelAdmin):
     list_filter = ('is_active',)
     search_fields = ['club__name']
 
-    # We can't change club after creation
-    readonly_fields = ('club',)
+    # We can't change club after creation or the balance
+    readonly_fields = ('club', 'balance')
 
     def has_add_permission(self, request):
         """
@@ -62,8 +62,8 @@ class NoteUserAdmin(admin.ModelAdmin):
     date_hierarchy = 'user__date_joined'
     ordering = ['-user__date_joined']
 
-    # We can't change user after creation
-    readonly_fields = ('user',)
+    # We can't change user after creation or the balance
+    readonly_fields = ('user', 'balance')
 
     def has_add_permission(self, request):
         """

note/models/notes.py

@@ -7,17 +7,16 @@ from django.db import models
 from django.db.models.signals import post_save
 from django.dispatch import receiver
 from django.utils.translation import gettext_lazy as _
+from polymorphic.models import PolymorphicModel
 
 """
 Defines each note types
 """
 
 
-class Note(models.Model):
+class Note(PolymorphicModel):
     """
     An model, use to add transactions capabilities
-
-    We do not use an abstract model to simplify the transfer between two notes.
     """
     balance = models.IntegerField(
         verbose_name=_('account balance'),
@@ -57,6 +56,9 @@ class NoteUser(Note):
         verbose_name = _("one's note")
         verbose_name_plural = _("users note")
 
+    def __str__(self):
+        return _("%(user)s's note") % {'user': str(self.user)}
+
 
 class NoteClub(Note):
     """

note/models/transactions.py

@@ -26,6 +26,7 @@ class TransactionTemplate(models.Model):
     )
     amount = models.PositiveIntegerField(
         verbose_name=_('amount'),
+        help_text=_('in centimes'),
     )
     template_type = models.CharField(
         verbose_name=_('type'),