jambo/parser/__init__.py

@@ -7,6 +7,7 @@ from .const_type_parser import ConstTypeParser
 from .enum_type_parser import EnumTypeParser
 from .float_type_parser import FloatTypeParser
 from .int_type_parser import IntTypeParser
+from .null_type_parser import NullTypeParser
 from .object_type_parser import ObjectTypeParser
 from .ref_type_parser import RefTypeParser
 from .string_type_parser import StringTypeParser
@@ -22,6 +23,7 @@ __all__ = [
     "BooleanTypeParser",
     "FloatTypeParser",
     "IntTypeParser",
+    "NullTypeParser",
     "ObjectTypeParser",
     "StringTypeParser",
     "RefTypeParser",

jambo/parser/null_type_parser.py

@@ -0,0 +1,18 @@
+from jambo.parser._type_parser import GenericTypeParser
+from jambo.types.type_parser_options import TypeParserOptions
+
+from typing_extensions import Unpack
+
+
+class NullTypeParser(GenericTypeParser):
+    mapped_type = type(None)
+
+    json_schema_type = "type:null"
+
+    def from_properties_impl(
+        self, name, properties, **kwargs: Unpack[TypeParserOptions]
+    ):
+        mapped_properties = self.mappings_properties_builder(properties, **kwargs)
+        mapped_properties["default"] = None
+
+        return self.mapped_type, mapped_properties

tests/parser/test_null_type_parser.py

@@ -0,0 +1,29 @@
+from jambo.parser import NullTypeParser
+
+from unittest import TestCase
+
+
+class TestNullTypeParser(TestCase):
+    def test_null_parser_no_options(self):
+        parser = NullTypeParser()
+
+        properties = {"type": "null"}
+
+        type_parsing, type_validator = parser.from_properties_impl(
+            "placeholder", properties
+        )
+
+        self.assertEqual(type_parsing, type(None))
+        self.assertEqual(type_validator, {"default": None})
+
+    def test_null_parser_with_invalid_default(self):
+        parser = NullTypeParser()
+
+        properties = {"type": "null", "default": "invalid"}
+
+        type_parsing, type_validator = parser.from_properties_impl(
+            "placeholder", properties
+        )
+
+        self.assertEqual(type_parsing, type(None))
+        self.assertEqual(type_validator, {"default": None})

tests/test_schema_converter.py

@@ -657,3 +657,23 @@ class TestSchemaConverter(TestCase):
 
         with self.assertRaises(ValueError):
             Model(name="Canada")
+
+    def test_null_type_parser(self):
+        schema = {
+            "title": "Test",
+            "type": "object",
+            "properties": {
+                "a_thing": {"type": "null"},
+            },
+        }
+
+        Model = SchemaConverter.build(schema)
+
+        obj = Model()
+        self.assertIsNone(obj.a_thing)
+
+        obj = Model(a_thing=None)
+        self.assertIsNone(obj.a_thing)
+
+        with self.assertRaises(ValueError):
+            Model(a_thing="not none")