Fix admin API gaps for users, exchange checks, and parser logs

src/apps/exchange/services.py

@@ -29,6 +29,27 @@ class ExchangeConnectionService:
         "parsers.FinancialReportLine",
     ]
 
+    @classmethod
+    def test_connection_payload(cls, **payload) -> dict[str, str]:
+        """Проверить подключение и структуру без сохранения в БД."""
+        connection = ExchangeConnection(is_active=False, **payload)
+        alias = cls.test_connection(connection)
+        cls.validate_target_structure(
+            connection=connection,
+            alias=alias,
+            schema_name=connection.schema_name,
+        )
+
+        with suppress(Exception):
+            connections[alias].close()
+        with suppress(Exception):
+            connections.databases.pop(alias, None)
+
+        return {
+            "status": "success",
+            "message": "Подключение и структура целевой БД валидны.",
+        }
+
     @classmethod
     @transaction.atomic
     def create_active_connection_and_prepare(cls, **payload) -> ExchangeConnection:
@@ -456,4 +477,7 @@ class ExchangeConnectionService:
     ) -> None:
         connection.last_checked_at = timezone.now()
         connection.last_error = error_message
-        connection.save(update_fields=["last_checked_at", "last_error", "updated_at"])
+        if connection.pk:
+            connection.save(
+                update_fields=["last_checked_at", "last_error", "updated_at"]
+            )