refactor(currencies): DEPRECATE SYNTH FINANCE

app/apps/currencies/migrations/0020_migrate_synth_finance_services.py

@@ -0,0 +1,51 @@
+# Generated by Django 5.2.5 on 2025-08-17 06:25
+
+from django.db import migrations
+
+# The new value we are migrating to
+NEW_SERVICE_TYPE = "frankfurter"
+# The old values we are deprecating
+OLD_SERVICE_TYPE_TO_UPDATE = "synth_finance"
+OLD_SERVICE_TYPE_TO_DELETE = "synth_finance_stock"
+
+
+def forwards_func(apps, schema_editor):
+    """
+    Forward migration:
+    - Deletes all ExchangeRateService instances with service_type 'synth_finance_stock'.
+    - Updates all ExchangeRateService instances with service_type 'synth_finance' to 'frankfurter'.
+    """
+    ExchangeRateService = apps.get_model("currencies", "ExchangeRateService")
+    db_alias = schema_editor.connection.alias
+
+    # 1. Delete the SYNTH_FINANCE_STOCK entries
+    ExchangeRateService.objects.using(db_alias).filter(
+        service_type=OLD_SERVICE_TYPE_TO_DELETE
+    ).delete()
+
+    # 2. Update the SYNTH_FINANCE entries to FRANKFURTER
+    ExchangeRateService.objects.using(db_alias).filter(
+        service_type=OLD_SERVICE_TYPE_TO_UPDATE
+    ).update(service_type=NEW_SERVICE_TYPE, api_key=None)
+
+
+def backwards_func(apps, schema_editor):
+    """
+    Backward migration: This operation is not safely reversible.
+    - We cannot know which 'frankfurter' services were originally 'synth_finance'.
+    - The deleted 'synth_finance_stock' services cannot be recovered.
+    We will leave this function empty to allow migrating backwards without doing anything.
+    """
+    pass
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        # Add the previous migration file here
+        ("currencies", "0019_alter_exchangerateservice_service_type"),
+    ]
+
+    operations = [
+        migrations.RunPython(forwards_func, reverse_code=backwards_func),
+    ]