Description
The OnDeleteType type alias in sqlmodel/main.py (line 91) is defined as:
OnDeleteType = Literal["CASCADE", "SET NULL", "RESTRICT"]
The SQL standard defines 5 referential actions for ON DELETE / ON UPDATE:
CASCADESET NULLSET DEFAULTRESTRICTNO ACTION
SQLAlchemy's ForeignKey(ondelete=...) accepts any string and its documentation explicitly lists all 5 as valid values.
Impact
NO ACTION is the default behavior in PostgreSQL and most databases. Developers who want to be explicit in their schema (common in migration-driven workflows with Alembic) cannot express this without type errors.SET DEFAULT is used when a foreign key column has a server_default and the parent row is deleted. This is supported by PostgreSQL, MySQL, and SQLite.
A developer hitting this gets a confusing mypy/pyright error on a perfectly valid schema definition. The only workarounds are casting to Any or dropping down to sa_column.
Fix
OnDeleteType = Literal["CASCADE", "SET NULL", "SET DEFAULT", "RESTRICT", "NO ACTION"]
One-line change.
Description
The
OnDeleteTypetype alias insqlmodel/main.py(line 91) is defined as:The SQL standard defines 5 referential actions for
ON DELETE/ON UPDATE:CASCADESET NULLSET DEFAULTRESTRICTNO ACTIONSQLAlchemy's
ForeignKey(ondelete=...)accepts any string and its documentation explicitly lists all 5 as valid values.Impact
NO ACTIONis the default behavior in PostgreSQL and most databases. Developers who want to be explicit in their schema (common in migration-driven workflows with Alembic) cannot express this without type errors.SET DEFAULTis used when a foreign key column has aserver_defaultand the parent row is deleted. This is supported by PostgreSQL, MySQL, and SQLite.A developer hitting this gets a confusing mypy/pyright error on a perfectly valid schema definition. The only workarounds are casting to
Anyor dropping down tosa_column.Fix
One-line change.