python_dto_mappers.utils
========================

.. py:module:: python_dto_mappers.utils

.. autoapi-nested-parse::

   Mapping utilities for partial updates and chaining.



Functions
---------

.. autoapisummary::

   python_dto_mappers.utils.extract_changed_fields
   python_dto_mappers.utils.chain_map


Module Contents
---------------

.. py:function:: extract_changed_fields(original: pydantic.BaseModel, update_dto: pydantic.BaseModel, exclude: Optional[Set[str]] = None) -> Dict[str, Any]

   Extract only changed fields for partial updates (PATCH).

   Compares original object with update DTO and returns only fields
   that have changed. Useful for HTTP PATCH operations.

   Args:
       original: Original object
       update_dto: Update DTO with new values
       exclude: Fields to exclude from comparison

   Returns:
       Dictionary with only changed fields

   Example:
       >>> original = User(id=1, name="John", email="john@example.com")
       >>> update = UserUpdateDTO(name="Jane", email="john@example.com")
       >>> changed = extract_changed_fields(original, update)
       >>> # {'name': 'Jane'}


.. py:function:: chain_map(source: Any, through: List[Type]) -> Any

   Chain multiple mappings in sequence.

   Applies multiple type transformations in order, useful for
   ORM → Domain → DTO conversions.

   Args:
       source: Source object to map
       through: List of target types to map through

   Returns:
       Final mapped object

   Example:
       >>> # ORM → Domain → DTO
       >>> dto = chain_map(
       ...     orm_user,
       ...     through=[DomainUser, UserDTO]
       ... )