feat(data-masking): add support for Pydantic models, dataclasses, and standard classes (#6413)

* feat(data-masking): support masking of Pydantic models, dataclasses, and standard classes (#3473)

* feat(data_masking): support complex input types via robust prepare_data() with and updated tests

* docs(data-masking): add support docs for Pydantic, dataclasses, and custom classes and updated test code

* docs(data-masking): update examples to use Lambda function entry points for supported input types and updated codebase

* refactoring prepare_data method

---------

Co-authored-by: Leandro Damascena <lcdama@amazon.pt>

Author: VatsalGoel3

aws_lambda_powertools/utilities/data_masking/base.py

@@ -6,6 +6,7 @@
 
 from __future__ import annotations
 
+import dataclasses
 import functools
 import logging
 import warnings
@@ -27,6 +28,51 @@
 logger = logging.getLogger(__name__)
 
 
+def prepare_data(data: Any, _visited: set[int] | None = None) -> Any:
+    """
+    Recursively convert complex objects into dictionaries or simple types.
+    Handles dataclasses, Pydantic models, and prevents circular references.
+    """
+    _visited = _visited or set()
+
+    # Handle circular references and primitive types
+    data_id = id(data)
+    if data_id in _visited or isinstance(data, (str, int, float, bool, type(None))):
+        return data
+
+    _visited.add(data_id)
+
+    # Define handlers as (condition, transformer) pairs
+    handlers: list[tuple[Callable[[Any], bool], Callable[[Any], Any]]] = [
+        # Dataclasses
+        (lambda x: hasattr(x, "__dataclass_fields__"), lambda x: prepare_data(dataclasses.asdict(x), _visited)),
+        # Pydantic models
+        (lambda x: callable(getattr(x, "model_dump", None)), lambda x: prepare_data(x.model_dump(), _visited)),
+        # Objects with dict() method
+        (
+            lambda x: callable(getattr(x, "dict", None)) and not isinstance(x, dict),
+            lambda x: prepare_data(x.dict(), _visited),
+        ),
+        # Dictionaries
+        (
+            lambda x: isinstance(x, dict),
+            lambda x: {prepare_data(k, _visited): prepare_data(v, _visited) for k, v in x.items()},
+        ),
+        # Lists, tuples, sets
+        (lambda x: isinstance(x, (list, tuple, set)), lambda x: type(x)(prepare_data(item, _visited) for item in x)),
+        # Objects with __dict__
+        (lambda x: hasattr(x, "__dict__"), lambda x: prepare_data(vars(x), _visited)),
+    ]
+
+    # Find and apply the first matching handler
+    for condition, transformer in handlers:
+        if condition(data):
+            return transformer(data)
+
+    # Default fallback
+    return data
+
+
 class DataMasking:
     """
     The DataMasking class orchestrates erasing, encrypting, and decrypting
@@ -93,6 +139,7 @@ def encrypt(
             data_masker = DataMasking(provider=encryption_provider)
             encrypted = data_masker.encrypt({"secret": "value"})
         """
+        data = prepare_data(data)
         return self._apply_action(
             data=data,
             fields=None,
@@ -135,7 +182,7 @@ def decrypt(
             data_masker = DataMasking(provider=encryption_provider)
             encrypted = data_masker.decrypt(encrypted_data)
         """
-
+        data = prepare_data(data)
         return self._apply_action(
             data=data,
             fields=None,
@@ -184,6 +231,7 @@ def erase(
         Any
             The data with sensitive information erased or masked.
         """
+        data = prepare_data(data)
         if masking_rules:
             return self._apply_masking_rules(data=data, masking_rules=masking_rules)
         else:

docs/utilities/data_masking.md

@@ -440,21 +440,41 @@ Note that the return will be a deserialized JSON and your desired fields updated
 
 ### Data serialization
 
-???+ note "Current limitations"
-    1. Python classes, `Dataclasses`, and `Pydantic models` are not supported yet.
+???+ tip "Extended input support"
+    We support `Pydantic models`, `Dataclasses`, and custom classes with `dict()` or `__dict__` for input.
+
+    These types are automatically converted into dictionaries before `masking` and `encrypting` operations. Please not that we **don't convert back** to the original type, and the returned object will be a dictionary.
 
 Before we traverse the data structure, we perform two important operations on input data:
 
 1. If `JSON string`, **deserialize** using default or provided deserializer.
-2. If `dictionary`, **normalize** into `JSON` to prevent traversing unsupported data types.
-
-When decrypting, we revert the operation to restore the original data structure.
+2. If `dictionary or complex types`, **normalize** into `JSON` to prevent traversing unsupported data types.
 
 For compatibility or performance, you can optionally pass your own JSON serializer and deserializer to replace `json.dumps` and `json.loads` respectively:
 
-```python hl_lines="17-18" title="advanced_custom_serializer.py"
---8<-- "examples/data_masking/src/advanced_custom_serializer.py"
-```
+=== "Working with custom types"
+
+    ```python
+    --8<-- "examples/data_masking/src/working_with_custom_types.py"
+    ```
+
+=== "Working with Pydantic"
+
+    ```python
+    --8<-- "examples/data_masking/src/working_with_pydantic_types.py"
+    ```
+
+=== "Working with dataclasses"
+
+    ```python
+    --8<-- "examples/data_masking/src/working_with_dataclass_types.py"
+    ```
+
+=== "Working with serializer"
+
+    ```python
+    --8<-- "examples/data_masking/src/advanced_custom_serializer.py"
+    ```
 
 ### Using multiple keys
 

examples/data_masking/src/working_with_custom_types.py

@@ -0,0 +1,17 @@
+from aws_lambda_powertools.utilities.data_masking import DataMasking
+
+data_masker = DataMasking()
+
+
+class User:
+    def __init__(self, name, age):
+        self.name = name
+        self.age = age
+
+    def dict(self):
+        return {"name": self.name, "age": self.age}
+
+
+def lambda_handler(event, context):
+    user = User("powertools", 42)
+    return data_masker.erase(user, fields=["age"])

examples/data_masking/src/working_with_dataclass_types.py

@@ -0,0 +1,16 @@
+from dataclasses import dataclass
+
+from aws_lambda_powertools.utilities.data_masking import DataMasking
+
+data_masker = DataMasking()
+
+
+@dataclass
+class User:
+    name: str
+    age: int
+
+
+def lambda_handler(event, context):
+    user = User(name="powertools", age=42)
+    return data_masker.erase(user, fields=["age"])

examples/data_masking/src/working_with_pydantic_types.py

@@ -0,0 +1,15 @@
+from pydantic import BaseModel
+
+from aws_lambda_powertools.utilities.data_masking import DataMasking
+
+data_masker = DataMasking()
+
+
+class User(BaseModel):
+    name: str
+    age: int
+
+
+def lambda_handler(event, context):
+    user = User(name="powertools", age=42)
+    return data_masker.erase(user, fields=["age"])