Merge pull request #12 from anikolaienko/feature/deepcopy

Deepcopy feature

CHANGELOG.md

@@ -1,3 +1,8 @@
+1.2.0 - 2022/10/25
+* [g-pichler] Ability to disable deepcopy on mapping: `use_deepcopy` flag in `map` method.
+* [g-pichler] Improved error text when no spec function exists for `target class`.
+* Updated doc comments.
+
 1.1.3 - 2022/10/07
 * [g-pichler] Added support for SQLAlchemy models mapping
 * Upgraded code checking tool and improved code formatting

README.md

@@ -3,7 +3,7 @@
 # py-automapper
 
 **Version**
-1.1.3
+1.2.0
 
 **Author**
 anikolaienko
@@ -32,6 +32,7 @@ Table of Contents:
 - [Usage](#usage)
   - [Different field names](#different-field-names)
   - [Overwrite field value in mapping](#overwrite-field-value-in-mapping)
+  - [Disable Deepcopy](#disable-deepcopy)
   - [Extensions](#extensions)
   - [Pydantic/FastAPI Support](#pydanticfastapi-support)
   - [TortoiseORM Support](#tortoiseorm-support)
@@ -124,6 +125,46 @@ print(vars(public_user_info))
 # {'full_name': 'John Cusack', 'profession': 'engineer'}
 ```
 
+## Disable Deepcopy
+By default, py-automapper performs a recursive `copy.deepcopy()` call on all attributes when copying from source object into target class instance.
+This makes sure that changes in the attributes of the source do not affect the target and vice versa.
+If you need your target and source class share same instances of child objects, set `use_deepcopy=False` in `map` function.
+
+```python
+from dataclasses import dataclass
+from automapper import mapper
+
+@dataclass
+class Address:
+    street: str
+    number: int
+    zip_code: int
+    city: str
+
+class PersonInfo:
+    def __init__(self, name: str, age: int, address: Address):
+        self.name = name
+        self.age = age
+        self.address = address
+
+class PublicPersonInfo:
+    def __init__(self, name: str, address: Address):
+        self.name = name
+        self.address = address
+
+address = Address(street="Main Street", number=1, zip_code=100001, city='Test City')
+info = PersonInfo('John Doe', age=35, address=address)
+
+# default deepcopy behavior
+public_info = mapper.to(PublicPersonInfo).map(info)
+print("Target public_info.address is same as source address: ", address is public_info.address)
+# Target public_info.address is same as source address: False
+
+# disable deepcopy
+public_info = mapper.to(PublicPersonInfo).map(info, use_deepcopy=False)
+print("Target public_info.address is same as source address: ", address is public_info.address)
+# Target public_info.address is same as source address: True
+```
 
 ## Extensions
 `py-automapper` has few predefined extensions for mapping support to classes for frameworks:

automapper/mapper.py

@@ -32,17 +32,17 @@
 __PRIMITIVE_TYPES = {int, float, complex, str, bytes, bytearray, bool}
 
 
-def is_sequence(obj: Any) -> bool:
+def _is_sequence(obj: Any) -> bool:
     """Check if object implements `__iter__` method"""
     return hasattr(obj, "__iter__")
 
 
-def is_subscriptable(obj: Any) -> bool:
+def _is_subscriptable(obj: Any) -> bool:
     """Check if object implements `__get_item__` method"""
     return hasattr(obj, "__get_item__")
 
 
-def is_primitive(obj: Any) -> bool:
+def _is_primitive(obj: Any) -> bool:
     """Check if object type is primitive"""
     return type(obj) in __PRIMITIVE_TYPES
 
@@ -65,19 +65,31 @@ def map(
         *,
         skip_none_values: bool = False,
         fields_mapping: FieldsMap = None,
+        use_deepcopy: bool = True,
     ) -> T:
-        """Produces output object mapped from source object and custom arguments
+        """Produces output object mapped from source object and custom arguments.
+
+        Args:
+            obj (S): _description_
+            skip_none_values (bool, optional): Skip None values when creating `target class` obj. Defaults to False.
+            fields_mapping (FieldsMap, optional): Custom mapping.
+                Specify dictionary in format {"field_name": value_object}. Defaults to None.
+            use_deepcopy (bool, optional): Apply deepcopy to all child objects when copy from source to target object.
+                Defaults to True.
 
-        Parameters:
-            skip_none_values - do not map fields that has None value
-            fields_mapping - mapping for fields with different names
+        Raises:
+            CircularReferenceError: Circular references in `source class` object are not allowed yet.
+
+        Returns:
+            T: instance of `target class` with mapped values from `source class` or custom `fields_mapping` dictionary.
         """
         return self.__mapper._map_common(
             obj,
             self.__target_cls,
             set(),
             skip_none_values=skip_none_values,
             fields_mapping=fields_mapping,
+            use_deepcopy=use_deepcopy,
         )
 
 
@@ -94,10 +106,9 @@ def __init__(self) -> None:
     def add_spec(self, classifier: Type[T], spec_func: SpecFunction[T]) -> None:
         """Add a spec function for all classes in inherited from base class.
 
-        Parameters:
-            * classifier - base class to identify all descendant classes
-            * spec_func - returns a list of fields (List[str]) for target class
-            that are accepted in constructor
+        Args:
+            classifier (ClassifierFunction[T]): base class to identify all descendant classes.
+            spec_func (SpecFunction[T]): get list of fields (List[str]) for `target class` to be passed in constructor.
         """
         ...
 
@@ -107,11 +118,10 @@ def add_spec(
     ) -> None:
         """Add a spec function for all classes identified by classifier function.
 
-        Parameters:
-            * classifier - boolean predicate that identifies a group of classes
-            by certain characteristics: if class has a specific method or a field, etc.
-            * spec_func - returns a list of fields (List[str]) for target class
-            that are accepted in constructor
+        Args:
+            classifier (ClassifierFunction[T]): boolean predicate that identifies a group of classes
+                by certain characteristics: if class has a specific method or a field, etc.
+            spec_func (SpecFunction[T]): get list of fields (List[str]) for `target class` to be passed in constructor.
         """
         ...
 
@@ -144,14 +154,19 @@ def add(
     ) -> None:
         """Adds mapping between object of `source class` to an object of `target class`.
 
-        Parameters
-        ----------
-        source_cls : Type
-            Source class to map from
-        target_cls : Type
-            Target class to map to
-        override : bool, optional
-            Override existing `source class` mapping to use new `target class`
+        Args:
+            source_cls (Type[S]): Source class to map from
+            target_cls (Type[T]): Target class to map to
+            override (bool, optional): Override existing `source class` mapping to use new `target class`.
+                Defaults to False.
+            fields_mapping (FieldsMap, optional): Custom mapping.
+                Specify dictionary in format {"field_name": value_object}. Defaults to None.
+
+        Raises:
+            DuplicatedRegistrationError: Same mapping for `source class` was added.
+            Only one mapping per source class can exist at a time for now.
+            You can specify target class manually using `mapper.to(target_cls)` method
+            or use `override` argument to replace existing mapping.
         """
         if source_cls in self._mappings and not override:
             raise DuplicatedRegistrationError(
@@ -165,8 +180,26 @@ def map(
         *,
         skip_none_values: bool = False,
         fields_mapping: FieldsMap = None,
+        use_deepcopy: bool = True,
     ) -> T:  # type: ignore [type-var]
-        """Produces output object mapped from source object and custom arguments"""
+        """Produces output object mapped from source object and custom arguments
+
+        Args:
+            obj (object): Source object to map to `target class`.
+            skip_none_values (bool, optional): Skip None values when creating `target class` obj. Defaults to False.
+            fields_mapping (FieldsMap, optional): Custom mapping.
+                Specify dictionary in format {"field_name": value_object}. Defaults to None.
+            use_deepcopy (bool, optional): Apply deepcopy to all child objects when copy from source to target object.
+                Defaults to True.
+
+        Raises:
+            MappingError: No `target class` specified to be mapped into.
+                Register mappings using `mapped.add(...)` or specify `target class` using `mapper.to(target_cls).map()`.
+            CircularReferenceError: Circular references in `source class` object are not allowed yet.
+
+        Returns:
+            T: instance of `target class` with mapped values from `source class` or custom `fields_mapping` dictionary.
+        """
         obj_type = type(obj)
         if obj_type not in self._mappings:
             raise MappingError(f"Missing mapping type for input type {obj_type}")
@@ -196,6 +229,7 @@ def map(
             set(),
             skip_none_values=skip_none_values,
             fields_mapping=common_fields_mapping,
+            use_deepcopy=use_deepcopy,
         )
 
     def _get_fields(self, target_cls: Type[T]) -> Iterable[str]:
@@ -208,15 +242,16 @@ def _get_fields(self, target_cls: Type[T]) -> Iterable[str]:
             if classifier(target_cls):
                 return self._classifier_specs[classifier](target_cls)
 
+        target_cls_name = getattr(target_cls, "__name__", type(target_cls))
         raise MappingError(
-            f"No spec function is added for base class of {type(target_cls)}"
+            f"No spec function is added for base class of {target_cls_name!r}"
         )
 
     def _map_subobject(
         self, obj: S, _visited_stack: Set[int], skip_none_values: bool = False
     ) -> Any:
         """Maps subobjects recursively"""
-        if is_primitive(obj):
+        if _is_primitive(obj):
             return obj
 
         obj_id = id(obj)
@@ -231,7 +266,7 @@ def _map_subobject(
         else:
             _visited_stack.add(obj_id)
 
-            if is_sequence(obj):
+            if _is_sequence(obj):
                 if isinstance(obj, dict):
                     result = {
                         k: self._map_subobject(
@@ -262,12 +297,25 @@ def _map_common(
         _visited_stack: Set[int],
         skip_none_values: bool = False,
         fields_mapping: FieldsMap = None,
+        use_deepcopy: bool = True,
     ) -> T:
-        """Produces output object mapped from source object and custom arguments
-
-        Parameters:
-            skip_none_values - do not map fields that has None value
-            fields_mapping - fields mappings for fields with different names
+        """Produces output object mapped from source object and custom arguments.
+
+        Args:
+            obj (S): Source object to map to `target class`.
+            target_cls (Type[T]): Target class to map to.
+            _visited_stack (Set[int]): Visited child objects. To avoid infinite recursive calls.
+            skip_none_values (bool, optional): Skip None values when creating `target class` obj. Defaults to False.
+            fields_mapping (FieldsMap, optional): Custom mapping.
+                Specify dictionary in format {"field_name": value_object}. Defaults to None.
+            use_deepcopy (bool, optional): Apply deepcopy to all child objects when copy from source to target object.
+                Defaults to True.
+
+        Raises:
+            CircularReferenceError: Circular references in `source class` object are not allowed yet.
+
+        Returns:
+            T: Instance of `target class` with mapped fields.
         """
         obj_id = id(obj)
 
@@ -278,7 +326,7 @@ def _map_common(
         target_cls_fields = self._get_fields(target_cls)
 
         mapped_values: Dict[str, Any] = {}
-        is_obj_subscriptable = is_subscriptable(obj)
+        is_obj_subscriptable = _is_subscriptable(obj)
         for field_name in target_cls_fields:
             if (
                 (fields_mapping and field_name in fields_mapping)
@@ -293,9 +341,12 @@ def _map_common(
                     value = obj[field_name]  # type: ignore [index]
 
                 if value is not None:
-                    mapped_values[field_name] = self._map_subobject(
-                        value, _visited_stack, skip_none_values
-                    )
+                    if use_deepcopy:
+                        mapped_values[field_name] = self._map_subobject(
+                            value, _visited_stack, skip_none_values
+                        )
+                    else:  # if use_deepcopy is False, simply assign value to target obj.
+                        mapped_values[field_name] = value
                 elif not skip_none_values:
                     mapped_values[field_name] = None
 
@@ -304,5 +355,12 @@ def _map_common(
         return cast(target_cls, target_cls(**mapped_values))  # type: ignore [valid-type]
 
     def to(self, target_cls: Type[T]) -> MappingWrapper[T]:
-        """Specify target class to map source object to"""
+        """Specify `target class` to which map `source class` object.
+
+        Args:
+            target_cls (Type[T]): Target class.
+
+        Returns:
+            MappingWrapper[T]: Mapping wrapper. Use `map` method to perform mapping now.
+        """
         return MappingWrapper[T](self, target_cls)

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "py-automapper"
-version = "1.1.3"
+version = "1.2.0"
 description = "Library for automatically mapping one object to another"
 authors = ["Andrii Nikolaienko <[email protected]>"]
 license = "MIT"