fix: serializer omit None values as expected (#136)

Signed-off-by: Jan Kowalleck <jan.kowalleck@gmail.com>

serializable/__init__.py

@@ -436,6 +436,11 @@ def as_xml(self: Any, view_: Optional[Type[ViewType]] = None,
                     elif prop_info.is_enum:
                         v = v.value
 
+                    if v is None:
+                        v = prop_info.get_none_value_for_view(view_=view_)
+                    if v is None:
+                        continue
+
                     this_e_attributes[_namespace_element_name(new_key, xmlns)] = \
                         _xs_string_mod_apply(str(v), prop_info.xml_string_config)
 
@@ -453,9 +458,6 @@ def as_xml(self: Any, view_: Optional[Type[ViewType]] = None,
                 # Skip as rendering for a view and this Property is not registered form this View
                 continue
 
-            if v is None:
-                v = prop_info.get_none_value_for_view(view_=view_)
-
             new_key = BaseNameFormatter.decode_handle_python_builtins_and_keywords(name=k)
 
             if not prop_info:
@@ -464,6 +466,8 @@ def as_xml(self: Any, view_: Optional[Type[ViewType]] = None,
             if not prop_info.is_xml_attribute:
                 new_key = prop_info.custom_names.get(SerializationType.XML, new_key)
 
+                if v is None:
+                    v = prop_info.get_none_value_for_view(view_=view_)
                 if v is None:
                     SubElement(this_e, _namespace_element_name(tag_name=new_key, xmlns=xmlns))
                     continue

tests/fixtures/the-phoenix-project-bookedition-none.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "George Spafford",
+    "Gene Kim",
+    "Kevin Behr"
+  ],
+  "edition": {
+    "name": "Preview Edition"
+  },
+  "id": "f3758bf0-0ff7-4366-a5e5-c209d4352b2d",
+  "isbnNumber": "978-1942788294",
+  "publishDate": "2018-04-16",
+  "publisher": {
+    "name": "IT Revolution Press LLC"
+  },
+  "rating": 9.8,
+  "title": "{J} The Phoenix Project",
+  "type": "fiction"
+}

tests/fixtures/the-phoenix-project-bookedition-none.xml

@@ -0,0 +1,14 @@
+<book isbnNumber="978-1942788294">
+    <id>f3758bf0-0ff7-4366-a5e5-c209d4352b2d</id>
+    <title>{X} The Phoenix Project</title>
+    <edition>Preview Edition</edition>
+    <publishDate>2018-04-16</publishDate>
+    <author>Kevin Behr</author>
+    <author>George Spafford</author>
+    <author>Gene Kim</author>
+    <type>fiction</type>
+    <publisher>
+        <name>IT Revolution Press LLC</name>
+    </publisher>
+    <rating>9.8</rating>
+</book>

tests/model.py

@@ -97,6 +97,22 @@ def xml_deserialize(cls, o: str) -> str:
         return re.sub(r'^\{X} ', '', o)
 
 
+class BookEditionHelper(BaseHelper):
+
+    @classmethod
+    def serialize(cls, o: Any) -> Optional[int]:
+        return o \
+            if isinstance(o, int) and o > 0 \
+            else None
+
+    @classmethod
+    def deserialize(cls, o: Any) -> int:
+        try:
+            return int(o)
+        except Exception:
+            return 1
+
+
 @serializable.serializable_class
 class Chapter:
 
@@ -170,6 +186,7 @@ def __init__(self, *, number: int, name: str) -> None:
 
     @property
     @serializable.xml_attribute()
+    @serializable.type_mapping(BookEditionHelper)
     def number(self) -> int:
         return self._number
 
@@ -469,6 +486,22 @@ def stock_ids(self) -> Set[StockId]:
 
 # endregion ThePhoenixProject_unnormalized
 
+# region ThePhoenixProject_attr_serialized_none
+
+# a case where an attribute is serialized to `None` and deserialized from it
+ThePhoenixProject_attr_serialized_none = Book(
+    title='The Phoenix Project',
+    isbn='978-1942788294',
+    publish_date=date(year=2018, month=4, day=16),
+    authors=['Gene Kim', 'Kevin Behr', 'George Spafford'],
+    publisher=Publisher(name='IT Revolution Press LLC'),
+    edition=BookEdition(number=0, name='Preview Edition'),
+    id=UUID('f3758bf0-0ff7-4366-a5e5-c209d4352b2d'),
+    rating=Decimal('9.8')
+)
+
+# endregion ThePhoenixProject_attr_serialized_none
+
 if __name__ == '__main__':
     tpp_as_xml = ThePhoenixProject.as_xml()  # type:ignore[attr-defined]
     tpp_as_json = ThePhoenixProject.as_json()  # type:ignore[attr-defined]

tests/test_json.py

@@ -26,11 +26,21 @@
     SnakeCasePropertyNameFormatter,
 )
 from tests.base import FIXTURES_DIRECTORY, BaseTestCase
-from tests.model import Book, SchemaVersion2, SchemaVersion3, SchemaVersion4, ThePhoenixProject, ThePhoenixProject_v1
+from tests.model import (
+    Book,
+    SchemaVersion2,
+    SchemaVersion3,
+    SchemaVersion4,
+    ThePhoenixProject,
+    ThePhoenixProject_attr_serialized_none,
+    ThePhoenixProject_v1,
+)
 
 
 class TestJson(BaseTestCase):
 
+    # region test_serialize
+
     def test_serialize_tfp_cc(self) -> None:
         CurrentFormatter.formatter = CamelCasePropertyNameFormatter
         with open(os.path.join(FIXTURES_DIRECTORY, 'the-phoenix-project-camel-case.json')) as expected_json:
@@ -130,3 +140,8 @@ def test_deserialize_tfp_sc(self) -> None:
             self.assertEqual(ThePhoenixProject_v1.publisher, book.publisher)
             self.assertEqual(ThePhoenixProject_v1.chapters, book.chapters)
             self.assertEqual(ThePhoenixProject_v1.rating, book.rating)
+
+    def test_serialize_attr_none(self) -> None:
+        CurrentFormatter.formatter = CamelCasePropertyNameFormatter
+        with open(os.path.join(FIXTURES_DIRECTORY, 'the-phoenix-project-bookedition-none.json')) as expected_json:
+            self.assertEqualJson(expected_json.read(), ThePhoenixProject_attr_serialized_none.as_json())

tests/test_xml.py

@@ -36,6 +36,7 @@
     SchemaVersion3,
     SchemaVersion4,
     ThePhoenixProject,
+    ThePhoenixProject_attr_serialized_none,
     ThePhoenixProject_unnormalized,
     ThePhoenixProject_v1,
 )
@@ -129,6 +130,11 @@ def test_serialize_unnormalized(self) -> None:
         with open(os.path.join(FIXTURES_DIRECTORY, 'the-phoenix-project-camel-case-1-v4.xml')) as expected_xml:
             self.assertEqualXml(expected_xml.read(), ThePhoenixProject_unnormalized.as_xml(SchemaVersion4))
 
+    def test_serialize_attr_none(self) -> None:
+        CurrentFormatter.formatter = CamelCasePropertyNameFormatter
+        with open(os.path.join(FIXTURES_DIRECTORY, 'the-phoenix-project-bookedition-none.xml')) as expected_xml:
+            self.assertEqualXml(expected_xml.read(), ThePhoenixProject_attr_serialized_none.as_xml(SchemaVersion4))
+
     # endregion test_serialize
 
     # region test_deserialize