Automatically link SpecialTransactions and their proxies

apps/treasury/apps.py

@@ -2,9 +2,24 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 from django.apps import AppConfig
+from django.db.models.signals import post_save
 from django.utils.translation import gettext_lazy as _
 
 
 class TreasuryConfig(AppConfig):
     name = 'treasury'
     verbose_name = _('Treasury')
+
+    def ready(self):
+        """
+        Define app internal signals to interact with other apps
+        """
+
+        from . import signals
+        from note.models import SpecialTransaction
+        from treasury.models import SpecialTransactionProxy
+        post_save.connect(signals.save_special_transaction, sender=SpecialTransaction)
+
+        # If the treasury app was disabled, we ensure that each special transaction is linked to a proxy
+        for transaction in SpecialTransaction.objects.filter(specialtransactionproxy=None):
+            SpecialTransactionProxy.objects.create(transaction=transaction, remittance=None)

apps/treasury/models.py

@@ -9,6 +9,10 @@ from note.models import NoteSpecial, SpecialTransaction
 
 
 class Invoice(models.Model):
+    """
+    An invoice model that can generate a true invoice
+    """
+
     id = models.PositiveIntegerField(
         primary_key=True,
         verbose_name=_("Invoice identifier"),
@@ -57,6 +61,10 @@ class Invoice(models.Model):
 
 
 class Product(models.Model):
+    """
+    Product that appear on an invoice.
+    """
+
     invoice = models.ForeignKey(
         Invoice,
         on_delete=models.PROTECT,
@@ -89,6 +97,10 @@ class Product(models.Model):
 
 
 class Remittance(models.Model):
+    """
+    Treasurers want to regroup checks or bank transfers in bank remittances.
+    """
+
     date = models.DateTimeField(
         auto_now_add=True,
         verbose_name=_("Date"),
@@ -132,6 +144,12 @@ class Remittance(models.Model):
 
 
 class SpecialTransactionProxy(models.Model):
+    """
+    In order to keep modularity, we don't that the Note app depends on the treasury app.
+    That's why we create a proxy in this app, to link special transactions and remittances.
+    If it isn't very clean, that makes what we want.
+    """
+
     transaction = models.OneToOneField(
         SpecialTransaction,
         on_delete=models.CASCADE,

apps/treasury/signals.py

+# Copyright (C) 2018-2020 by BDE ENS Paris-Saclay
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from treasury.models import SpecialTransactionProxy
+
+
+def save_special_transaction(instance, created, **kwargs):
+    """
+    When a special transaction is created, we create its linked proxy
+    """
+    if created:
+        SpecialTransactionProxy.objects.create(transaction=instance, remittance=None).save()