Merge pull request #190 from dapper91/dev

- dynamic model creation support added.

Author: dapper91

CHANGELOG.rst

@@ -1,6 +1,12 @@
 Changelog
 =========
 
+2.10.0 (2024-05-09)
+------------------
+
+- dynamic model creation support added. See https://pydantic-xml.readthedocs.io/en/latest/pages/misc.html#dynamic-model-creation
+
+
 2.9.2 (2024-04-19)
 ------------------
 

README.rst

@@ -42,7 +42,6 @@ Features
 What is not supported?
 ______________________
 
-- `dynamic model creation <https://docs.pydantic.dev/usage/models/#dynamic-model-creation>`_
 - `dataclasses <https://docs.pydantic.dev/usage/dataclasses/>`_
 
 Getting started

docs/source/pages/misc.rst

@@ -215,6 +215,21 @@ Standard library serializer also supports customizations.
 For more information see :py:func:`xml.etree.ElementTree.tostring`,
 
 
+Dynamic model creation
+~~~~~~~~~~~~~~~~~~~~~~
+
+There are some cases when it is necessary to create a model using runtime information to describe model fields.
+For this ``pydantic-xml`` provides the :py:func:`pydantic_xml.create_model` function to create a model on the fly:
+
+.. literalinclude:: ../../../examples/snippets/dynamic_model_creation.py
+    :language: python
+    :start-after: model-start
+    :end-before: model-end
+
+Field specification syntax is similar to ``pydantic`` one. For more information
+see the `documentation <https://docs.pydantic.dev/latest/concepts/models/#dynamic-model-creation>`_.
+
+
 Mypy
 ~~~~
 

examples/snippets/dynamic_model_creation.py

@@ -0,0 +1,27 @@
+from pydantic_xml import attr, create_model
+
+# [model-start]
+Company = create_model(
+    'Company',
+    trade_name=(str, attr(name='trade-name')),
+    type=(str, attr()),
+)
+
+# [model-end]
+
+
+# [xml-start]
+xml_doc = '''
+<Company trade-name="SpaceX" type="Private"/>
+'''  # [xml-end]
+
+# [json-start]
+json_doc = '''
+{
+    "trade_name": "SpaceX",
+    "type": "Private"
+}
+'''  # [json-end]
+
+company = Company.from_xml(xml_doc)
+assert company == Company.model_validate_json(json_doc)

pydantic_xml/__init__.py

@@ -4,7 +4,7 @@
 
 from . import config, errors, model
 from .errors import ModelError, ParsingError
-from .model import BaseXmlModel, RootXmlModel, attr, computed_attr, computed_element, element, wrapped
+from .model import BaseXmlModel, RootXmlModel, attr, computed_attr, computed_element, create_model, element, wrapped
 
 __all__ = (
     'BaseXmlModel',
@@ -16,6 +16,7 @@
     'wrapped',
     'computed_attr',
     'computed_element',
+    'create_model',
     'errors',
     'model',
 )

pydantic_xml/model.py

@@ -19,6 +19,7 @@
 
 __all__ = (
     'attr',
+    'create_model',
     'element',
     'wrapped',
     'computed_attr',
@@ -250,6 +251,70 @@ def wrapped(
     )
 
 
+Model = TypeVar('Model', bound='BaseXmlModel')
+
+
+def create_model(
+        __model_name: str,
+        *,
+        __tag__: Optional[str] = None,
+        __ns__: Optional[str] = None,
+        __nsmap__: Optional[NsMap] = None,
+        __ns_attrs__: Optional[bool] = None,
+        __skip_empty__: Optional[bool] = None,
+        __search_mode__: Optional[SearchMode] = None,
+        __base__: Union[Type[Model], Tuple[Type[Model], ...], None] = None,
+        __module__: Optional[str] = None,
+        **kwargs: Any,
+) -> Type[Model]:
+    """
+    Dynamically creates a new pydantic-xml model.
+
+    :param __model_name: model name
+    :param __tag__: element tag
+    :param __ns__: element namespace
+    :param __nsmap__: element namespace map
+    :param __ns_attrs__: use namespaced attributes
+    :param __skip_empty__: skip empty elements (elements without sub-elements, attributes and text)
+    :param __search_mode__: element search mode
+    :param __base__: model base class
+    :param __module__: module name that the model belongs to
+    :param kwargs: pydantic model creation arguments.
+                   See https://docs.pydantic.dev/latest/api/base_model/#pydantic.create_model.
+
+    :return: created model
+    """
+
+    cls_kwargs = kwargs.setdefault('__cls_kwargs__', {})
+    cls_kwargs['metaclass'] = XmlModelMeta
+
+    cls_kwargs['tag'] = __tag__
+    cls_kwargs['ns'] = __ns__
+    cls_kwargs['nsmap'] = __nsmap__
+    cls_kwargs['ns_attrs'] = __ns_attrs__
+    cls_kwargs['skip_empty'] = __skip_empty__
+    cls_kwargs['search_mode'] = __search_mode__
+
+    model_base: Union[Type[BaseModel], Tuple[Type[BaseModel], ...]] = __base__ or BaseXmlModel
+
+    if model_config := kwargs.pop('__config__', None):
+        # since pydantic create_model function forbids __base__ and __config__ arguments together,
+        # we create base pydantic class with __config__ and inherit from it
+        BaseWithConfig = pd.create_model(
+            f'{__model_name}Base',
+            __module__=__module__,  # type: ignore[arg-type]
+            __config__=model_config,
+        )
+        if not isinstance(model_base, tuple):
+            model_base = (model_base, BaseWithConfig)
+        else:
+            model_base = (*model_base, BaseWithConfig)
+
+    model = pd.create_model(__model_name, __base__=model_base, **kwargs)
+
+    return typing.cast(Type[Model], model)
+
+
 @te.dataclass_transform(kw_only_default=True, field_specifiers=(attr, element, wrapped, pd.Field))
 class XmlModelMeta(ModelMetaclass):
     """
@@ -305,6 +370,7 @@ def __init_subclass__(
         :param ns: element namespace
         :param nsmap: element namespace map
         :param ns_attrs: use namespaced attributes
+        :param skip_empty: skip empty elements (elements without sub-elements, attributes and text)
         :param search_mode: element search mode
         """
 

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pydantic-xml"
-version = "2.9.2"
+version = "2.10.0"
 description = "pydantic xml extension"
 authors = ["Dmitry Pershin <dapper1291@gmail.com>"]
 license = "Unlicense"