k

backend/alembic/versions/ac9c7b76419b_add_set_null_to_chat_session_persona_fk.py

@@ -0,0 +1,42 @@
+"""Add SET NULL cascade to chat_session.persona_id foreign key
+
+Revision ID: ac9c7b76419b
+Revises: 73e9983e5091
+Create Date: 2026-01-17 18:10:00.000000
+
+"""
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "ac9c7b76419b"
+down_revision = "73e9983e5091"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Drop the existing foreign key constraint (no cascade behavior)
+    op.drop_constraint("fk_chat_session_persona_id", "chat_session", type_="foreignkey")
+    # Recreate with SET NULL on delete, so deleting a persona sets
+    # chat_session.persona_id to NULL instead of blocking the delete
+    op.create_foreign_key(
+        "fk_chat_session_persona_id",
+        "chat_session",
+        "persona",
+        ["persona_id"],
+        ["id"],
+        ondelete="SET NULL",
+    )
+
+
+def downgrade() -> None:
+    # Revert to original constraint without cascade behavior
+    op.drop_constraint("fk_chat_session_persona_id", "chat_session", type_="foreignkey")
+    op.create_foreign_key(
+        "fk_chat_session_persona_id",
+        "chat_session",
+        "persona",
+        ["persona_id"],
+        ["id"],
+    )

backend/onyx/db/models.py

@@ -2045,7 +2045,7 @@ class ChatSession(Base):
         ForeignKey("user.id", ondelete="CASCADE"), nullable=True
     )
     persona_id: Mapped[int | None] = mapped_column(
-        ForeignKey("persona.id"), nullable=True
+        ForeignKey("persona.id", ondelete="SET NULL"), nullable=True
     )
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
     # This chat created by OnyxBot