Getting more patch logic in.

crudkit/core/service.py

@@ -10,6 +10,7 @@ from sqlalchemy.orm.attributes import InstrumentedAttribute
 from sqlalchemy.sql import operators
 from sqlalchemy.sql.elements import UnaryExpression, ColumnElement
 
+from crudkit.core import deep_diff, diff_to_patch
 from crudkit.core.base import Version
 from crudkit.core.spec import CRUDSpec
 from crudkit.core.types import OrderSpec, SeekWindow
@@ -660,16 +661,41 @@ class CRUDService(Generic[T]):
         session = self.session
         obj = session.get(self.model, id)
         if not obj:
-            raise ValueError(f"{self.model.__name__} with ID {id} not found.")
-        valid_fields = {c.name for c in self.model.__table__.columns}
-        unknown = set(data) - valid_fields
+            raise ValueError("f{self.model.__name__} id ID {id} not found.")
+
+        # Only touch real columns
+        valid = {c.name for c in self.model.__table__.columns}
+        unknown = set(data) - valid
         if unknown:
             raise ValueError(f"Unknown fields: {', '.join(sorted(unknown))}")
+
+        # BEFORE snapshot (non-lazy, columns-only is fine)
+        before = obj.as_dict()
+
+        # Apply patch
         for k, v in data.items():
-            if k in valid_fields:
-                setattr(obj, k, v)
+            setattr(obj, k, v)
+
+        # If nothing changed at ORM level, bail early
+        if not session.is_modified(obj, include_collections=False):
+            return obj
+
         session.commit()
-        self._log_version("update", obj, actor)
+
+        after = obj.as_dict()
+
+        diff = deep_diff(
+            before,
+            after,
+            ignore_keys={"updated_at", "created_at", "id"},
+            list_mode="index",
+        )
+
+        # If somehow no diff, do not spam versions
+        if not(diff["added"] or diff["removed"] or diff["changed"]):
+            return obj
+
+        self._log_version("update", obj, actor, metadata={"diff": diff})
         return obj
 
     def delete(self, id: int, hard: bool = False, actor = None):
@@ -688,17 +714,19 @@ class CRUDService(Generic[T]):
 
     def _log_version(self, change_type: str, obj: T, actor=None, metadata: dict | None = None):
         session = self.session
+        snapshot = {}
         try:
-            data = obj.as_dict()
+            snapshot = obj.as_dict()
         except Exception:
-            data = {"error": "Failed to serialize object."}
+            snapshot = {"error": "serialize failed"}
+
         version = Version(
             model_name=self.model.__name__,
             object_id=obj.id,
             change_type=change_type,
-            data=data,
+            data=snapshot,
             actor=str(actor) if actor else None,
-            meta=metadata
+            meta=metadata or None,
         )
         session.add(version)
         session.commit()