fix: add SET DEFAULT and NO ACTION to OnDeleteType

The OnDeleteType literal that types Field(ondelete=...) only listed
CASCADE, SET NULL and RESTRICT, so type checkers rejected the other two
standard SQL referential actions, SET DEFAULT and NO ACTION, even though
both are valid at runtime and emit correct ON DELETE DDL via SQLAlchemy.

Add the two missing actions to the literal and cover them with a
parametrized regression test asserting the generated foreign key and
DDL.

Author: anxkhn

sqlmodel/main.py

@@ -87,7 +87,7 @@
     | Mapping[int, Union["IncEx", bool]]
     | Mapping[str, Union["IncEx", bool]]
 )
-OnDeleteType = Literal["CASCADE", "SET NULL", "RESTRICT"]
+OnDeleteType = Literal["CASCADE", "SET NULL", "SET DEFAULT", "RESTRICT", "NO ACTION"]
 
 
 def __dataclass_transform__(

tests/test_main.py

@@ -3,6 +3,7 @@
 import pytest
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import RelationshipProperty
+from sqlalchemy.schema import CreateTable
 from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
 
 
@@ -216,3 +217,26 @@ class Hero(SQLModel, table=True):
     assert len(foreign_keys) == 1
     assert foreign_keys[0].ondelete == "CASCADE"
     assert team_id_column.nullable is False
+
+
+@pytest.mark.parametrize("ondelete", ["SET DEFAULT", "NO ACTION"])
+def test_foreign_key_ondelete_referential_actions(clear_sqlmodel, ondelete):
+    class Team(SQLModel, table=True):
+        id: int | None = Field(default=None, primary_key=True)
+
+    class Hero(SQLModel, table=True):
+        id: int | None = Field(default=None, primary_key=True)
+        team_id: int | None = Field(
+            default=None, foreign_key="team.id", ondelete=ondelete
+        )
+
+    engine = create_engine("sqlite://")
+    SQLModel.metadata.create_all(engine)
+
+    hero_table = Hero.__table__  # type: ignore[attr-defined]
+    foreign_keys = list(hero_table.c.team_id.foreign_keys)
+    assert len(foreign_keys) == 1
+    assert foreign_keys[0].ondelete == ondelete
+
+    ddl = str(CreateTable(hero_table).compile(engine))
+    assert f"ON DELETE {ondelete}" in ddl