Fix random display of configuration type in offers. Bug was caused by django 1.7 app registry which is dict type. With this type python decide the order. So sometimes, VPNConfiguration is ordered after Configuration. (Not 100% sure what i'm saying)

Fixed by remove choices param from model and choices construction from model init method The choice list is now generated at admin form level.
This modification not change database schema.
By the way I've allowed the configuration type to be empty, so we can create offer without configuration type (ADSL FDN for ex)

coin/offers/admin.py

@@ -8,15 +8,17 @@ from coin.offers.models import Offer, OfferSubscription
 from coin.offers.offersubscription_filter import\
             OfferSubscriptionTerminationFilter,\
             OfferSubscriptionCommitmentFilter
+from coin.offers.forms import OfferAdminForm
 import autocomplete_light
 
 
 class OfferAdmin(admin.ModelAdmin):
-    list_display = ('configuration_type', 'name', 'billing_period', 'period_fees',
+    list_display = ('get_configuration_type_display', 'name', 'billing_period', 'period_fees',
                     'initial_fees')
     list_display_links = ('name',)
     list_filter = ('configuration_type',)
     search_fields = ['name']
+    form = OfferAdminForm
 
     # def get_readonly_fields(self, request, obj=None):
     #     if obj:

coin/offers/fixtures/offers.json

@@ -40,7 +40,7 @@
             "name": "Marque blanche FDN",
             "initial_fees": "70.00",
             "period_fees": "32.00",
-            "configuration_type": "none"
+            "configuration_type": ""
         }
     },
     {
@@ -51,7 +51,7 @@
             "name": "Marque blanche FDN (préférentiel)",
             "initial_fees": "70.00",
             "period_fees": "28.00",
-            "configuration_type": "none"
+            "configuration_type": ""
         }
     }
 ]

coin/offers/forms.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from django.forms import ModelForm
+from django.forms.widgets import Select
+from coin.offers.models import Offer
+from coin.configuration.models import Configuration
+
+
+class OfferAdminForm(ModelForm):
+    class Meta:
+        model = Offer
+        widgets = {
+            'configuration_type' : Select(choices=(('','---------'),)+Configuration.get_configurations_choices_list())
+        }

coin/offers/migrations/0002_auto_20141009_2223.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('offers', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='offer',
+            name='configuration_type',
+            field=models.CharField(help_text='Type de configuration \xe0 utiliser avec cette offre', max_length=50, verbose_name='type de configuration', blank=True),
+        ),
+    ]

coin/offers/models.py

@@ -15,21 +15,10 @@ class Offer(models.Model):
     The choices list is dynamically generated at start in the __init__
     """
 
-    def __init__(self, *args, **kwargs):
-        from coin.configuration.models import Configuration
-        super(Offer, self).__init__(*args, **kwargs)
-        """
-        Génère automatiquement la liste de choix possibles de types
-        de configurations en fonction des classes enfants de Configuration
-        """
-        self._meta.get_field_by_name('configuration_type')[0]._choices = (
-            Configuration.get_configurations_choices_list())
-
     name = models.CharField(max_length=255, blank=False, null=False,
                             verbose_name="nom de l'offre")
     configuration_type = models.CharField(max_length=50,
-                            null=True,
-                            choices = (('',''),),
+                            blank=True,
                             verbose_name='type de configuration',
                             help_text="Type de configuration à utiliser avec cette offre")
     billing_period = models.IntegerField(blank=False, null=False, default=1,
@@ -49,17 +38,18 @@ class Offer(models.Model):
         """
         Renvoi le nom affichable du type de configuration
         """
+        from coin.configuration.models import Configuration
         for item in Configuration.get_configurations_choices_list():
             if item and self.configuration_type in item:
                 return item[1]
         return self.configuration_type
+    get_configuration_type_display.short_description = 'type de configuration'
 
     def __unicode__(self):
-        return '%s : %s - %d€ / %im' % (
-            self.get_configuration_type_display(),
-            self.name,
-            self.period_fees,
-            self.billing_period)
+        return '{name} - {period_fee}€ / {billing_period}m'.format(
+            name=self.name,
+            period_fee=self.period_fees,
+            billing_period=self.billing_period)
 
     class Meta:
         verbose_name = 'offre'