Fix GeometryField value conversion crashing on non-None values

GeometryField subclasses Field directly (single base), so the _FieldMeta
metaclass — which only auto-assigns field_type when there are multiple
bases — leaves field_type as None. The base to_python_value/to_db_value
converters then call isinstance(value, self.field_type), raising
TypeError: isinstance() arg 2 must be a type ... on any non-None value.

Declare field_type = str and parametrize as Field[str], mirroring the
fix applied to TSVectorField in #2237.

Author: gaoflow

tests/contrib/mysql/test_geometry_field.py

@@ -0,0 +1,26 @@
+from tortoise.contrib.mysql.fields import GeometryField
+
+
+def test_geometry_field_type() -> None:
+    """GeometryField must declare a concrete ``field_type``.
+
+    A single-base ``Field`` subclass does not get ``field_type`` assigned by the
+    ``_FieldMeta`` metaclass (that only fires for multiple bases), so an explicit
+    attribute is required. When it is missing, ``field_type`` is ``None`` and the
+    base value converters raise ``TypeError`` from ``isinstance(value, None)``.
+    """
+    assert GeometryField().field_type is str
+
+
+def test_geometry_field_to_python_value() -> None:
+    field = GeometryField()
+    # ``None`` must pass through untouched.
+    assert field.to_python_value(None) is None
+    # A concrete DB value must be converted without raising.
+    assert field.to_python_value("POINT(1 1)") == "POINT(1 1)"
+
+
+def test_geometry_field_to_db_value() -> None:
+    field = GeometryField()
+    assert field.to_db_value(None, None) is None
+    assert field.to_db_value("POINT(1 1)", None) == "POINT(1 1)"

tortoise/contrib/mysql/fields.py

@@ -10,8 +10,9 @@
     from tortoise.models import Model
 
 
-class GeometryField(Field):
+class GeometryField(Field[str]):
     SQL_TYPE = "GEOMETRY"
+    field_type = str
 
 
 class UUIDField(UUIDFieldBase):