A kind of initial commit

app/db/base.py

@@ -0,0 +1,18 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+
+
+def utcnow() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class TimestampMixin:
+    created_at: Mapped[datetime] = mapped_column(default=utcnow)
+    updated_at: Mapped[datetime] = mapped_column(default=utcnow, onupdate=utcnow)