ref: remove signals in favor of save() override

app/base/models/account.py

@@ -21,10 +21,10 @@ class Account(models.Model):
     def __str__(self):
         return f"{self.user}'s Konto"
 
-    # def change_balance(self, amount):
-    #     self.balance = self.balance - amount
-    #     self.save()
-    #     return True
+    def update_balance(self, amount: 'Decimal') -> None:
+        if amount:
+            self.balance += amount
+            self.save()
 
     # def lock(self):
     #     self.locked = True

app/base/models/booking.py

@@ -5,6 +5,7 @@ from django.urls import reverse
 
 from app.base.forms.fields import DateTimeField, TextField
 from app.base.forms.utils import datetime_now
+from app.base.models.transaction import Transaction
 
 from typing import TYPE_CHECKING
 if TYPE_CHECKING:
@@ -42,11 +43,14 @@ class Booking(models.Model):
             if self.end_time else '')
 
     def save(self, *args, **kwargs):
-        # update last_visit time of all involved persons
         prev = Booking.objects.get(pk=self.pk) if self.pk else None
 
         rv = super().save(*args, **kwargs)
 
+        # update Transaction
+        Transaction.upsertFromBooking(self)
+
+        # update last_visit time of all involved persons
         if prev and prev.user != self.user:
             prev.user.update_last_visit(None)
         if not prev or prev.user != self.user or \

app/base/models/person.py

@@ -59,6 +59,7 @@ class Person(models.Model):
         if self._state.adding:
             self.created = date.today()
             self.last_visit = date.today()
+            Account.objects.create(user=self)
         return super().save(*args, **kwargs)
 
     @property

app/base/models/transaction.py

@@ -38,4 +38,37 @@ class Transaction(models.Model):
     def save(self, *args, **kwargs):
         if self._state.adding:
             self.time_stamp = datetime_now()
+            self.account.update_balance(self.amount)
+        elif self.pk:  # basically an "else", but just to be sure
+            prev = Transaction.objects.get(pk=self.pk)
+            self.account.update_balance(self.amount - prev.amount)
+
         return super().save(*args, **kwargs)
+
+    def delete(self, *args, **kwargs):
+        self.account.update_balance(-self.amount)
+        return super().delete(*args, **kwargs)
+
+    @staticmethod
+    def upsertFromBooking(booking: 'Booking'):
+        amount = booking.calculated_price
+        should_exist = booking.end_time and amount
+        description = f'{booking.type.label} ({booking.duration or 0} Min)'
+
+        # Create or update existing Transaction
+        transaction = Transaction.objects.filter(booking=booking).first()
+        if transaction:
+            if should_exist:
+                transaction.amount = -amount
+                transaction.description = description
+                transaction.save()
+            else:
+                transaction.delete()
+
+        elif should_exist:
+            Transaction.objects.create(
+                account=booking.user.account,
+                amount=-amount,
+                description=description,
+                booking=booking,
+            )

app/base/signals/__init__.py

@@ -1,7 +0,0 @@
-from app.base.signals.booking import booking_post_save
-from app.base.signals.person import person_post_save
-from app.base.signals.transaction import (
-    transaction_pre_save,
-    transaction_post_save,
-    transaction_pre_delete
-)

app/base/signals/booking.py

@@ -1,29 +0,0 @@
-from django.db.models.signals import post_save
-from django.dispatch import receiver
-
-from app.base.models import Transaction, Booking
-
-
-@receiver(post_save, sender=Booking)
-def booking_post_save(sender, instance: Booking, created: bool, **kwargs):
-    amount = instance.calculated_price
-    with_transaction = instance.end_time and amount
-    description = f'{instance.type.label} ({instance.duration or 0} Min)'
-
-    # Create or update existing Transaction
-    transaction = Transaction.objects.filter(booking=instance).first()
-    if transaction:
-        if with_transaction:
-            transaction.amount = -amount
-            transaction.description = description
-            transaction.save()
-        else:
-            transaction.delete()
-
-    elif with_transaction:
-        Transaction.objects.create(
-            account=instance.user.account,
-            amount=-amount,
-            description=description,
-            booking=instance,
-        )

app/base/signals/person.py

@@ -1,9 +0,0 @@
-from django.dispatch import receiver
-from django.db.models.signals import post_save
-from app.base.models import Person, Account
-
-
-@receiver(post_save, sender=Person)
-def person_post_save(sender, instance: Person, created: bool, **kwargs):
-    if created:
-        Account.objects.create(user=instance)

app/base/signals/transaction.py

@@ -1,28 +0,0 @@
-from django.dispatch import receiver
-from django.db.models.signals import pre_save, post_save, pre_delete
-from app.base.models import Transaction
-
-
-@receiver(pre_save, sender=Transaction)
-def transaction_pre_save(sender, instance: Transaction, **kwargs):
-    if instance.pk:
-        pre_edit = Transaction.objects.get(pk=instance.pk)
-
-        if pre_edit.amount != instance.amount:
-            delta = pre_edit.amount - instance.amount
-            account = instance.account
-            account.balance = account.balance - delta
-            account.save()
-
-
-@receiver(post_save, sender=Transaction)
-def transaction_post_save(sender, instance: Transaction, created, **kwargs):
-    if created:
-        instance.account.balance += instance.amount
-        instance.account.save()
-
-
-@receiver(pre_delete, sender=Transaction)
-def transaction_pre_delete(sender, instance: Transaction, **kwargs):
-    instance.account.balance -= instance.amount
-    instance.account.save()