feat: json only field support

docs/source/pages/misc.rst

@@ -71,6 +71,16 @@ The following example illustrate how to serialize ``xs:list`` element:
     :language: python
 
 
+JSON only field
+~~~~~~~~~~~~~~~
+
+To prevent a field from serialization/deserialization only for xml format
+mark it with :py:class:`pydantic_xml.NoXml` annotation:
+
+.. literalinclude:: ../../../examples/snippets/py3.9/noxml.py
+  :language: python
+
+
 Optional type encoding
 ~~~~~~~~~~~~~~~~~~~~~~
 

examples/snippets/py3.9/noxml.py

@@ -0,0 +1,29 @@
+from typing import Annotated, Optional
+from xml.etree.ElementTree import canonicalize
+
+from pydantic_xml import BaseXmlModel, NoXml, element
+
+
+class Company(BaseXmlModel):
+    title: str = element()
+    website: Annotated[Optional[str], NoXml] = element(default=None)
+
+
+xml_doc = '''
+<Company>
+    <title>SpaceX</title>
+</Company>
+'''
+
+company = Company.from_xml(xml_doc)
+
+assert canonicalize(company.to_xml(), strip_text=True) == canonicalize(xml_doc, strip_text=True)
+
+json_doc = '''
+{
+    "title": "SpaceX",
+    "website": "https://spacex.com/"
+}
+'''
+company = Company.model_validate_json(json_doc)
+assert company.model_dump_json(indent=4) == json_doc.strip()

pydantic_xml/__init__.py

@@ -4,8 +4,8 @@
 
 from . import config, errors, model
 from .errors import ModelError, ParsingError
-from .fields import XmlFieldSerializer, XmlFieldValidator, attr, computed_attr, computed_element, element, wrapped
-from .fields import xml_field_serializer, xml_field_validator
+from .fields import NoXml, XmlFieldSerializer, XmlFieldValidator, attr, computed_attr, computed_element, element
+from .fields import wrapped, xml_field_serializer, xml_field_validator
 from .model import BaseXmlModel, RootXmlModel, create_model
 
 __all__ = (
@@ -23,6 +23,7 @@
     'model',
     'xml_field_serializer',
     'xml_field_validator',
+    'NoXml',
     'XmlFieldValidator',
     'XmlFieldSerializer',
 )

pydantic_xml/fields.py

@@ -21,13 +21,20 @@
     'xml_field_serializer',
     'xml_field_validator',
     'ComputedXmlEntityInfo',
+    'NoXml',
     'XmlEntityInfo',
     'XmlEntityInfoP',
     'XmlFieldSerializer',
     'XmlFieldValidator',
 )
 
 
+class NoXml:
+    """
+    Annotation to prevent field encoding or decoding for xml format only.
+    """
+
+
 class XmlEntityInfoP(typing.Protocol):
     location: Optional[EntityLocation]
     path: Optional[str]

pydantic_xml/serializers/factories/model.py

@@ -9,7 +9,7 @@
 import pydantic_xml as pxml
 from pydantic_xml import errors, utils
 from pydantic_xml.element import XmlElementReader, XmlElementWriter, is_element_nill, make_element_nill
-from pydantic_xml.fields import ComputedXmlEntityInfo, XmlEntityInfoP, extract_field_xml_entity_info
+from pydantic_xml.fields import ComputedXmlEntityInfo, NoXml, XmlEntityInfoP, extract_field_xml_entity_info
 from pydantic_xml.serializers.serializer import SearchMode, Serializer
 from pydantic_xml.typedefs import EntityLocation, Location, NsMap
 from pydantic_xml.utils import QName, merge_nsmaps, select_ns
@@ -76,6 +76,10 @@ def from_core_schema(cls, schema: pcs.ModelSchema, ctx: Serializer.Context) -> '
         fields_validation_aliases: Dict[str, str] = {}
         fields_serializers: Dict[str, Serializer] = {}
         for field_name, model_field in fields_schema['fields'].items():
+            field_info = model_cls.model_fields[field_name]
+            if NoXml in field_info.metadata:
+                continue
+
             if model_field.get('serialization_exclude', False):
                 fields_serialization_exclude.add(field_name)
 
@@ -84,7 +88,6 @@ def from_core_schema(cls, schema: pcs.ModelSchema, ctx: Serializer.Context) -> '
                 if isinstance(validation_alias, str):
                     fields_validation_aliases[field_name] = validation_alias
 
-            field_info = model_cls.model_fields[field_name]
             field_ctx = ctx.child(
                 field_name=field_name,
                 field_alias=field_alias,

tests/test_misc.py

@@ -6,7 +6,7 @@
 import pytest
 from helpers import assert_xml_equal
 
-from pydantic_xml import BaseXmlModel, RootXmlModel, attr, element, errors, wrapped
+from pydantic_xml import BaseXmlModel, NoXml, RootXmlModel, attr, element, errors, wrapped
 
 
 def test_xml_declaration():
@@ -441,3 +441,27 @@ class TestModel(BaseXmlModel, tag="model"):
         assert not error_value_input, error_str
     else:
         assert error_value_input, error_str
+
+
+@pytest.mark.skipif(sys.version_info < (3, 9), reason="requires python 3.9 and above")
+def test_no_xml_annotation():
+    from typing import Annotated
+
+    class TestModel(BaseXmlModel, tag="model"):
+        field1: str = element()
+        field2: Annotated[Optional[str], NoXml] = element(default=None)
+
+    expected_xml = '<model><field1>data1</field1></model>'
+    actual_obj = TestModel.from_xml(expected_xml)
+    expected_obj = TestModel(field1='data1')
+
+    assert actual_obj == expected_obj
+    actual_xml = actual_obj.to_xml(skip_empty=True)
+    assert_xml_equal(actual_xml, expected_xml.encode())
+
+    expected_json = {'field1': 'data1', 'field2': 'data2'}
+    actual_obj = TestModel.model_validate(expected_json)
+    expected_obj = TestModel(field1='data1', field2='data2')
+    assert actual_obj == expected_obj
+
+    assert actual_obj.model_dump() == expected_json