Configuration(pydantic_settings=[...]) (#525)

* Add implementation

* Update changelog

* Fix deepcopy()

* Add example

* Add tests

* Add docs

Author: rmk135

docs/main/changelog.rst

@@ -16,6 +16,7 @@ Develop
 - Add support of ``with`` statement for ``container.override_providers()`` method.
 - Add ``Configuration(yaml_files=[...])`` argument.
 - Add ``Configuration(ini_files=[...])`` argument.
+- Add ``Configuration(pydantic_settings=[...])`` argument.
 - Drop support of Python 3.4. There are no immediate breaking changes, but Dependency Injector
   will no longer be tested on Python 3.4 and any bugs will not be fixed.
 - Fix ``Dependency.is_defined`` attribute to always return boolean value.

docs/providers/configuration.rst

@@ -154,6 +154,21 @@ If you need to pass an argument to this call, use ``.from_pydantic()`` keyword a
 
    container.config.from_pydantic(Settings(), exclude={"optional"})
 
+Alternatively, you can provide a ``pydantic`` settings object over the configuration provider argument. In that case,
+the container will call ``config.from_pydantic()`` automatically:
+
+.. code-block:: python
+   :emphasize-lines: 3
+
+   class Container(containers.DeclarativeContainer):
+
+       config = providers.Configuration(pydantic_settings=[Settings()])
+
+
+   if __name__ == "__main__":
+       container = Container()  # Config is loaded from Settings()
+
+
 .. note::
 
    ``Dependency Injector`` doesn't install ``pydantic`` by default.

examples/providers/configuration/configuration_pydantic_init.py

@@ -0,0 +1,35 @@
+"""`Configuration` provider values loading example."""
+
+import os
+
+from dependency_injector import containers, providers
+from pydantic import BaseSettings, Field
+
+# Emulate environment variables
+os.environ["AWS_ACCESS_KEY_ID"] = "KEY"
+os.environ["AWS_SECRET_ACCESS_KEY"] = "SECRET"
+
+
+class AwsSettings(BaseSettings):
+
+    access_key_id: str = Field(env="aws_access_key_id")
+    secret_access_key: str = Field(env="aws_secret_access_key")
+
+
+class Settings(BaseSettings):
+
+    aws: AwsSettings = AwsSettings()
+    optional: str = Field(default="default_value")
+
+
+class Container(containers.DeclarativeContainer):
+
+    config = providers.Configuration(pydantic_settings=[Settings()])
+
+
+if __name__ == "__main__":
+    container = Container()
+
+    assert container.config.aws.access_key_id() == "KEY"
+    assert container.config.aws.secret_access_key() == "SECRET"
+    assert container.config.optional() == "default_value"