Allow Configuration provider to accept pydantic settings classes (#963)

Author: warmagedon007

docs/providers/configuration.rst

@@ -212,6 +212,19 @@ the container will call ``config.from_pydantic()`` automatically:
    if __name__ == "__main__":
        container = Container()  # Config is loaded from Settings()
 
+In addition, if you need the pydantic instance to be initialized on use, you can provide ``pydantic_settings.BaseSettings`` type instead.
+The container will initialize a pydantic instance on load without kwargs.
+
+.. 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 instance that is initialized
 
 .. note::
 

src/dependency_injector/providers.pyi

@@ -30,9 +30,12 @@ except ImportError:
     yaml = None
 
 try:
-    import pydantic
+    from pydantic_settings import BaseSettings as PydanticSettings
 except ImportError:
-    pydantic = None
+    try:
+        from pydantic import BaseSettings as PydanticSettings
+    except ImportError:
+        PydanticSettings = Any
 
 from . import resources
 
@@ -272,7 +275,7 @@ class Configuration(Object[Any]):
         ini_files: Optional[_Iterable[Union[Path, str]]] = None,
         yaml_files: Optional[_Iterable[Union[Path, str]]] = None,
         json_files: Optional[_Iterable[Union[Path, str]]] = None,
-        pydantic_settings: Optional[_Iterable[PydanticSettings]] = None,
+        pydantic_settings: Optional[_Iterable[Union[PydanticSettings, Type[PydanticSettings]]]] = None,
     ) -> None: ...
     def __enter__(self) -> _Self: ...
     def __exit__(self, *exc_info: Any) -> None: ...
@@ -292,8 +295,8 @@ class Configuration(Object[Any]):
     def set_yaml_files(self, files: _Iterable[Union[Path, str]]) -> _Self: ...
     def get_json_files(self) -> _List[Union[Path, str]]: ...
     def set_json_files(self, files: _Iterable[Union[Path, str]]) -> _Self: ...
-    def get_pydantic_settings(self) -> _List[PydanticSettings]: ...
-    def set_pydantic_settings(self, settings: _Iterable[PydanticSettings]) -> _Self: ...
+    def get_pydantic_settings(self) -> _List[Union[PydanticSettings, Type[PydanticSettings]]]: ...
+    def set_pydantic_settings(self, settings: _Iterable[Union[PydanticSettings, Type[PydanticSettings]]]) -> _Self: ...
     def load(self, required: bool = False, envs_required: bool = False) -> None: ...
     def get(self, selector: str) -> Any: ...
     def set(self, selector: str, value: Any) -> OverridingContext[P]: ...
@@ -319,7 +322,7 @@ class Configuration(Object[Any]):
         envs_required: bool = False,
     ) -> None: ...
     def from_pydantic(
-        self, settings: PydanticSettings, required: bool = False, **kwargs: Any
+        self, settings: Union[PydanticSettings, Type[PydanticSettings]], required: bool = False, **kwargs: Any
     ) -> None: ...
     def from_dict(self, options: _Dict[str, Any], required: bool = False) -> None: ...
     def from_env(
@@ -630,8 +633,3 @@ if yaml:
 
 else:
     class YamlLoader: ...
-
-if pydantic:
-    PydanticSettings = pydantic.BaseSettings
-else:
-    PydanticSettings = Any

src/dependency_injector/providers.pyx

@@ -157,10 +157,7 @@ cdef dict pydantic_settings_to_dict(settings, dict kwargs):
         )
 
     if isinstance(settings, type) and issubclass(settings, PydanticSettings):
-        raise Error(
-            "Got settings class, but expect instance: "
-            "instead \"{0}\" use \"{0}()\"".format(settings.__name__)
-        )
+        settings = settings()
 
     if not isinstance(settings, PydanticSettings):
         raise Error(

tests/typing/configuration.py

@@ -1,5 +1,5 @@
 from pathlib import Path
-from typing import Any, Dict
+from typing import Any, Dict, Type
 from typing_extensions import assert_type
 
 from pydantic_settings import BaseSettings as PydanticSettings
@@ -33,6 +33,8 @@
 
 config2.from_pydantic(PydanticSettings())
 
+config2.from_pydantic(PydanticSettings)
+
 # Test 3: to check as_*() methods
 config3 = providers.Configuration()
 int3 = config3.option.as_int()
@@ -80,14 +82,18 @@
 )
 config5_pydantic.set_pydantic_settings([PydanticSettings()])
 
-# NOTE: Using assignment since PydanticSettings is context-sensitive: conditional on whether pydantic is installed
-config5_pydantic_settings: list[PydanticSettings] = (
-    config5_pydantic.get_pydantic_settings()
-)
+config5_pydantic_settings = config5_pydantic.get_pydantic_settings()
+
+assert_type(config5_pydantic_settings, list[PydanticSettings | Type[PydanticSettings]])
 
 # Test 6: to check init arguments
 config6 = providers.Configuration(
     name="config",
     strict=True,
     default={},
 )
+
+# Test 7: pydantic class
+config7_pydantic_class = providers.Configuration(
+    pydantic_settings=[PydanticSettings]
+)

tests/unit/providers/configuration/test_from_pydantic_py36.py

@@ -168,21 +168,23 @@ def test_option_not_instance_of_settings(config):
 
 
 def test_subclass_instead_of_instance(config):
-    with raises(errors.Error) as error:
-        config.from_pydantic(Settings1)
-    assert error.value.args[0] == (
-        "Got settings class, but expect instance: "
-        "instead \"Settings1\" use \"Settings1()\""
-    )
+    config.from_pydantic(Settings1)
+
+    assert config() == {"section1": {"value1": 1}, "section2": {"value2": 2}}
+    assert config.section1() == {"value1": 1}
+    assert config.section1.value1() == 1
+    assert config.section2() == {"value2": 2}
+    assert config.section2.value2() == 2
 
 
 def test_option_subclass_instead_of_instance(config):
-    with raises(errors.Error) as error:
-        config.option.from_pydantic(Settings1)
-    assert error.value.args[0] == (
-        "Got settings class, but expect instance: "
-        "instead \"Settings1\" use \"Settings1()\""
-    )
+    config.option.from_pydantic(Settings1)
+
+    assert config.option() == {"section1": {"value1": 1}, "section2": {"value2": 2}}
+    assert config.option.section1() == {"value1": 1}
+    assert config.option.section1.value1() == 1
+    assert config.option.section2() == {"value2": 2}
+    assert config.option.section2.value2() == 2
 
 
 @mark.usefixtures("no_pydantic_module_installed")