fix: Type checking of None assignment to nullable fields (tortoise#2089)

* fix: Type checking of None assignment to nullable fields

* Update CHANGELOG

Author: henadzit

CHANGELOG.rst

@@ -10,6 +10,13 @@ Changelog
 1.0
 ===
 
+1.0.1 (unreleased)
+------------------
+Fixed
+^^^^^
+- Type checking of None assignment to nullable fields (#2089)
+
+
 1.0.0
 -----
 

tests/fields/type_checks.py

@@ -0,0 +1,189 @@
+"""
+This file contains the code that is meant to be checked by a type checker, not to be run as a test.
+"""
+
+from datetime import date, datetime, time, timedelta
+from decimal import Decimal
+from enum import Enum, IntEnum
+from uuid import UUID
+
+from tortoise.fields.data import (
+    BinaryField,
+    BooleanField,
+    CharEnumField,
+    CharField,
+    DateField,
+    DatetimeField,
+    DecimalField,
+    FloatField,
+    IntEnumField,
+    IntField,
+    TimeDeltaField,
+    TimeField,
+    UUIDField,
+)
+from tortoise.models import Model
+
+
+class Status(IntEnum):
+    PENDING = 1
+    ACTIVE = 2
+    INACTIVE = 3
+
+
+class Color(str, Enum):
+    RED = "red"
+    GREEN = "green"
+    BLUE = "blue"
+
+
+class InheretedFromIntField(IntField):
+    pass
+
+
+class TypeTestModel(Model):
+    # CharField fields
+    char_non_null = CharField(max_length=100, null=False)
+    char_nullable = CharField(max_length=100, null=True)
+
+    # IntField fields
+    int_non_null = IntField(null=False)
+    int_nullable = IntField(null=True)
+
+    # BooleanField fields
+    bool_non_null = BooleanField(null=False)
+    bool_nullable = BooleanField(null=True)
+
+    # DecimalField fields
+    decimal_non_null = DecimalField(max_digits=10, decimal_places=2, null=False)
+    decimal_nullable = DecimalField(max_digits=10, decimal_places=2, null=True)
+
+    # DatetimeField fields
+    datetime_non_null = DatetimeField(null=False)
+    datetime_nullable = DatetimeField(null=True)
+
+    # DateField fields
+    date_non_null = DateField(null=False)
+    date_nullable = DateField(null=True)
+
+    # TimeField fields
+    time_non_null = TimeField(null=False)
+    time_nullable = TimeField(null=True)
+
+    # TimeDeltaField fields
+    timedelta_non_null = TimeDeltaField(null=False)
+    timedelta_nullable = TimeDeltaField(null=True)
+
+    # FloatField fields
+    float_non_null = FloatField(null=False)
+    float_nullable = FloatField(null=True)
+
+    # UUIDField fields
+    uuid_non_null = UUIDField(null=False)
+    uuid_nullable = UUIDField(null=True)
+
+    # BinaryField fields
+    binary_non_null = BinaryField(null=False)
+    binary_nullable = BinaryField(null=True)
+
+    # Enum fields
+    int_enum_field_non_null = IntEnumField(enum_type=Status, null=False)
+    int_enum_field_nullable = IntEnumField(enum_type=Status, null=True)
+    char_enum_field_non_null = CharEnumField(enum_type=Color, max_length=10, null=False)
+    char_enum_field_nullable = CharEnumField(enum_type=Color, max_length=10, null=True)
+
+    # inhereted fields
+    inhereted_int_field_non_null = InheretedFromIntField(null=False)
+    inhereted_int_field_nullable = InheretedFromIntField(null=True)
+
+
+def test_char_field_nullability() -> None:
+    o = TypeTestModel(char_non_null="test", char_nullable="test")
+    o.char_nullable = None
+    o.char_non_null = "another test"
+
+
+def test_int_field_nullability() -> None:
+    o = TypeTestModel(char_non_null="test", int_non_null=42, int_nullable=42)
+    o.int_nullable = None
+    o.int_non_null = 100
+
+
+def test_bool_field_nullability() -> None:
+    o = TypeTestModel(char_non_null="test", bool_non_null=True, bool_nullable=True)
+    o.bool_nullable = None
+    o.bool_non_null = False
+
+
+def test_decimal_field_nullability() -> None:
+    o = TypeTestModel(
+        char_non_null="test", decimal_non_null=Decimal("10.50"), decimal_nullable=Decimal("10.50")
+    )
+    o.decimal_nullable = None
+    o.decimal_non_null = Decimal("20.75")
+
+
+def test_datetime_field_nullability() -> None:
+    now = datetime.now()
+    o = TypeTestModel(char_non_null="test", datetime_non_null=now, datetime_nullable=now)
+    o.datetime_nullable = None
+    o.datetime_non_null = datetime(2024, 1, 1, 12, 0, 0)
+
+
+def test_date_field_nullability() -> None:
+    today = date.today()
+    o = TypeTestModel(char_non_null="test", date_non_null=today, date_nullable=today)
+    o.date_nullable = None
+    o.date_non_null = date(2024, 1, 1)
+
+
+def test_time_field_nullability() -> None:
+    now_time = time(12, 0, 0)
+    o = TypeTestModel(char_non_null="test", time_non_null=now_time, time_nullable=now_time)
+    o.time_nullable = None
+    o.time_non_null = time(15, 30, 0)
+
+
+def test_timedelta_field_nullability() -> None:
+    delta = timedelta(days=1)
+    o = TypeTestModel(char_non_null="test", timedelta_non_null=delta, timedelta_nullable=delta)
+    o.timedelta_nullable = None
+    o.timedelta_non_null = timedelta(days=2)
+
+
+def test_float_field_nullability() -> None:
+    o = TypeTestModel(char_non_null="test", float_non_null=1.5, float_nullable=1.5)
+    o.float_nullable = None
+    o.float_non_null = 3.14
+
+
+def test_uuid_field_nullability() -> None:
+    test_uuid = UUID("12345678-1234-5678-1234-567812345678")
+    o = TypeTestModel(char_non_null="test", uuid_non_null=test_uuid, uuid_nullable=test_uuid)
+    o.uuid_nullable = None
+    o.uuid_non_null = UUID("87654321-4321-8765-4321-876543218765")
+
+
+def test_binary_field_nullability() -> None:
+    o = TypeTestModel(char_non_null="test", binary_non_null=b"data", binary_nullable=b"data")
+    o.binary_nullable = None
+    o.binary_non_null = b"new data"
+
+
+# TODO: add support for proper types when null=True for enum fields
+# def test_enum_fields() -> None:
+#     o = TypeTestModel(char_non_null="test", int_non_null=1, bool_non_null=True, float_non_null=1.0, binary_non_null=b"test")
+
+#     o.int_enum_field_nullable = None
+#     o.int_enum_field_non_null = Status.ACTIVE
+
+#     o.char_enum_field_nullable = None
+#     o.char_enum_field_non_null = Color.GREEN
+
+
+def test_inhereted_int_field() -> None:
+    o = TypeTestModel(
+        char_non_null="test", inhereted_int_field_non_null=42, inhereted_int_field_nullable=42
+    )
+    o.inhereted_int_field_nullable = None
+    o.inhereted_int_field_non_null = 100