fix part 3

backend/app/database/models/board.py

@@ -1,10 +1,10 @@
 """Board database model."""
 
-from datetime import datetime, timezone
+from datetime import datetime
 from typing import TYPE_CHECKING
 from uuid import UUID, uuid4
 
-from sqlalchemy import Boolean, DateTime, ForeignKey, String, Text
+from sqlalchemy import Boolean, DateTime, ForeignKey, String, Text, func
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.dialects.postgresql import UUID as PGUUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -42,9 +42,9 @@ class Board(Base):
         default=lambda: {"x": 0, "y": 0, "zoom": 1.0, "rotation": 0},
     )
 
-    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, server_default=func.now())
     updated_at: Mapped[datetime] = mapped_column(
-        DateTime, nullable=False, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc)
+        DateTime, nullable=False, server_default=func.now(), onupdate=func.now()
     )
     is_deleted: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
 

backend/app/database/models/board_image.py

@@ -1,10 +1,10 @@
 """BoardImage database model - junction table for boards and images."""
 
-from datetime import datetime, timezone
+from datetime import datetime
 from typing import TYPE_CHECKING
 from uuid import UUID, uuid4
 
-from sqlalchemy import DateTime, ForeignKey, Integer
+from sqlalchemy import DateTime, ForeignKey, Integer, func
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.dialects.postgresql import UUID as PGUUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -52,9 +52,9 @@ class BoardImage(Base):
         PGUUID(as_uuid=True), ForeignKey("groups.id", ondelete="SET NULL"), nullable=True
     )
 
-    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, server_default=func.now())
     updated_at: Mapped[datetime] = mapped_column(
-        DateTime, nullable=False, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc)
+        DateTime, nullable=False, server_default=func.now(), onupdate=func.now()
     )
 
     # Relationships

backend/app/database/models/comment.py

@@ -1,9 +1,8 @@
 """Comment model for board annotations."""
 
 import uuid
-from datetime import datetime, timezone
 
-from sqlalchemy import Boolean, Column, DateTime, ForeignKey, String, Text
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, String, Text, func
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import relationship
 
@@ -21,7 +20,7 @@ class Comment(Base):
     author_name = Column(String(100), nullable=False)
     content = Column(Text, nullable=False)
     position = Column(JSONB, nullable=True)  # Optional canvas position reference
-    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, nullable=False, server_default=func.now())
     is_deleted = Column(Boolean, nullable=False, default=False)
 
     # Relationships

backend/app/database/models/group.py

@@ -1,10 +1,10 @@
 """Group database model."""
 
-from datetime import datetime, timezone
+from datetime import datetime
 from typing import TYPE_CHECKING
 from uuid import UUID, uuid4
 
-from sqlalchemy import DateTime, ForeignKey, String, Text
+from sqlalchemy import DateTime, ForeignKey, String, Text, func
 from sqlalchemy.dialects.postgresql import UUID as PGUUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
@@ -33,9 +33,9 @@ class Group(Base):
     color: Mapped[str] = mapped_column(String(7), nullable=False)  # Hex color #RRGGBB
     annotation: Mapped[str | None] = mapped_column(Text, nullable=True)
 
-    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, server_default=func.now())
     updated_at: Mapped[datetime] = mapped_column(
-        DateTime, nullable=False, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc)
+        DateTime, nullable=False, server_default=func.now(), onupdate=func.now()
     )
 
     # Relationships

backend/app/database/models/image.py

@@ -1,10 +1,10 @@
 """Image database model."""
 
-from datetime import datetime, timezone
+from datetime import datetime
 from typing import TYPE_CHECKING
 from uuid import UUID, uuid4
 
-from sqlalchemy import BigInteger, DateTime, ForeignKey, Integer, String
+from sqlalchemy import BigInteger, DateTime, ForeignKey, Integer, String, func
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.dialects.postgresql import UUID as PGUUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -38,7 +38,7 @@ class Image(Base):
     height: Mapped[int] = mapped_column(Integer, nullable=False)
     image_metadata: Mapped[dict] = mapped_column(JSONB, nullable=False)
 
-    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, server_default=func.now())
     reference_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
 
     # Relationships

backend/app/database/models/share_link.py

@@ -1,9 +1,8 @@
 """ShareLink model for board sharing functionality."""
 
 import uuid
-from datetime import datetime, timezone
 
-from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String, func
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import relationship
 
@@ -19,7 +18,7 @@ class ShareLink(Base):
     board_id = Column(UUID(as_uuid=True), ForeignKey("boards.id", ondelete="CASCADE"), nullable=False)
     token = Column(String(64), unique=True, nullable=False, index=True)
     permission_level = Column(String(20), nullable=False)  # 'view-only' or 'view-comment'
-    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, nullable=False, server_default=func.now())
     expires_at = Column(DateTime, nullable=True)
     last_accessed_at = Column(DateTime, nullable=True)
     access_count = Column(Integer, nullable=False, default=0)

backend/app/database/models/user.py

@@ -1,9 +1,8 @@
 """User model for authentication and ownership."""
 
 import uuid
-from datetime import datetime, timezone
 
-from sqlalchemy import Boolean, Column, DateTime, String
+from sqlalchemy import Boolean, Column, DateTime, String, func
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import relationship
 
@@ -18,8 +17,8 @@ class User(Base):
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
     email = Column(String(255), unique=True, nullable=False, index=True)
     password_hash = Column(String(255), nullable=False)
-    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
-    updated_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, nullable=False, server_default=func.now())
+    updated_at = Column(DateTime, nullable=False, server_default=func.now(), onupdate=func.now())
     is_active = Column(Boolean, nullable=False, default=True)
 
     # Relationships