feat: add soft delete mixin and session

- Add SoftDeleteMixin class with deleted_at field
- Add SoftDeleteSession class that overrides delete method for soft deletes
- Add tests for soft delete functionality
- Fix datetime deprecation warning

Author: letsdeepchat

sqlmodel/soft_delete.py

@@ -0,0 +1,8 @@
+from datetime import datetime
+from typing import Optional
+
+from sqlmodel import Field
+
+
+class SoftDeleteMixin:
+    deleted_at: Optional[datetime] = Field(default=None, nullable=True)

sqlmodel/soft_delete_session.py

@@ -0,0 +1,18 @@
+from typing import Any
+
+from sqlmodel.orm.session import Session
+
+from sqlmodel.soft_delete import SoftDeleteMixin
+
+
+class SoftDeleteSession(Session):
+    def delete(self, instance: Any, hard_delete: bool = False) -> Any:
+        if not hard_delete and isinstance(instance, SoftDeleteMixin):
+            instance.deleted_at = self._now()
+            self.add(instance)
+            return instance
+        return super().delete(instance)
+
+    def _now(self) -> Any:
+        from datetime import datetime, timezone
+        return datetime.now(timezone.utc)

tests/test_session_delete.py

@@ -0,0 +1,61 @@
+import pytest
+from datetime import datetime
+from typing import Optional
+
+from sqlmodel import SQLModel, create_engine
+from sqlmodel.main import default_registry
+from sqlmodel.soft_delete import SoftDeleteMixin
+from sqlmodel.soft_delete_session import SoftDeleteSession
+
+
+from sqlmodel import Field
+
+class SoftDeleteHero(SQLModel, SoftDeleteMixin, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    name: str
+
+
+@pytest.fixture(autouse=True)
+def clear_sqlmodel():
+    # Local override to avoid global dispose
+    pass
+
+
+def test_soft_delete():
+    engine = create_engine("sqlite:///:memory:")
+    SQLModel.metadata.create_all(engine)
+
+    with SoftDeleteSession(engine) as session:
+        hero = SoftDeleteHero(name="Test Hero")
+        session.add(hero)
+        session.commit()
+
+        # Soft delete
+        session.delete(hero)
+        session.commit()
+
+        # Check soft deleted
+        assert hero.deleted_at is not None
+        assert isinstance(hero.deleted_at, datetime)
+
+        # Refresh to confirm
+        session.refresh(hero)
+        assert hero.deleted_at is not None
+
+
+def test_hard_delete():
+    engine = create_engine("sqlite:///:memory:")
+    SQLModel.metadata.create_all(engine)
+
+    with SoftDeleteSession(engine) as session:
+        hero = SoftDeleteHero(name="Test Hero")
+        session.add(hero)
+        session.commit()
+
+        # Hard delete
+        session.delete(hero, hard_delete=True)
+        session.commit()
+
+        # Check hard deleted (would raise if not handled, but since hard delete, it's gone)
+        # In SQLAlchemy, after hard delete, the object is detached
+        assert hero.id is None or session.get(SoftDeleteHero, hero.id) is None