Allow assignment of NO_VALUE to fields

src/infi/clickhouse_orm/models.py

@@ -170,7 +170,7 @@ class Model(metaclass=ModelBase):
         This may raise a `ValueError`.
         '''
         field = self.get_field(name)
-        if field:
+        if field and (value != NO_VALUE):
             try:
                 value = field.to_python(value, pytz.utc)
                 field.validate(value)

tests/test_alias_fields.py

@@ -60,6 +60,10 @@ class AliasFieldsTest(unittest.TestCase):
     def test_default_value(self):
         instance = ModelWithAliasFields()
         self.assertEqual(instance.alias_str, NO_VALUE)
+        # Check that NO_VALUE can be assigned to a field
+        instance.str_field = NO_VALUE
+        # Check that NO_VALUE can be assigned when creating a new instance
+        instance2 = ModelWithAliasFields(**instance.to_dict())
 
 
 class ModelWithAliasFields(Model):