Enum support and strip annotations.

pydantic_settings/sources.py

@@ -8,6 +8,7 @@
 from abc import ABC, abstractmethod
 from collections import deque
 from dataclasses import is_dataclass
+from enum import Enum
 from pathlib import Path
 from types import FunctionType
 from typing import TYPE_CHECKING, Any, Dict, List, Mapping, Sequence, Tuple, TypeVar, Union, cast
@@ -27,7 +28,7 @@
 if TYPE_CHECKING:
     from pydantic_settings.main import BaseSettings
 
-from argparse import SUPPRESS, ArgumentParser, _ArgumentGroup, _SubParsersAction
+from argparse import SUPPRESS, Action, ArgumentParser, Namespace, _ArgumentGroup, _SubParsersAction
 
 DotenvType = Union[Path, str, List[Union[Path, str]], Tuple[Union[Path, str], ...]]
 
@@ -50,6 +51,22 @@ class _CliPositionalArg:
 CliPositionalArg = Annotated[T, _CliPositionalArg]
 
 
+class _CliEnumAction(Action):
+    """
+    CLI argparse action handler for enum types
+    """
+
+    def __init__(self, **kwargs: Any):
+        self._enum = kwargs.pop('type')
+        kwargs['choices'] = tuple(val.name for val in self._enum)
+        super().__init__(**kwargs)
+
+    def __call__(
+        self, parser: ArgumentParser, namespace: Namespace, value: Any, option_string: str | None = None
+    ) -> None:
+        setattr(namespace, self.dest, self._enum[value])
+
+
 class EnvNoneType(str):
     pass
 
@@ -917,6 +934,10 @@ def _add_fields_to_parser(
                     kwargs['action'] = 'append'
                     if _annotation_contains_types(field_info.annotation, (dict, Mapping), is_include_origin=True):
                         self._cli_dict_arg_names.append(kwargs['dest'])
+                elif lenient_issubclass(field_info.annotation, Enum):
+                    kwargs['type'] = field_info.annotation
+                    kwargs['action'] = _CliEnumAction
+                    del kwargs['metavar']
 
                 arg_name = f'{arg_prefix.replace(subcommand_prefix, "", 1)}{field_name}'
                 if _CliPositionalArg in field_info.metadata:
@@ -972,6 +993,8 @@ def _metavar_format_list(self, args: list[str]) -> str:
 
     def _metavar_format_recurse(self, obj: Any) -> str:
         """Pretty metavar representation of a type. Adapts logic from `pydantic._repr.display_as_type`."""
+        while get_origin(obj) == Annotated:
+            obj = get_args(obj)[0]
         if isinstance(obj, FunctionType):
             return obj.__name__
         elif obj is ...:

tests/test_settings.py

@@ -4,6 +4,7 @@
 import typing
 import uuid
 from datetime import datetime, timezone
+from enum import IntEnum
 from pathlib import Path
 from typing import Any, Callable, Dict, Generic, List, Optional, Set, Tuple, Type, TypeVar, Union
 
@@ -14,6 +15,7 @@
     AliasChoices,
     AliasPath,
     BaseModel,
+    DirectoryPath,
     Field,
     HttpUrl,
     Json,
@@ -2302,6 +2304,22 @@ class Cfg(BaseSettings):
     assert cfg.model_dump() == {'child': {'name': 'new name a', 'diff_a': 'new diff a'}}
 
 
+def test_cli_enum():
+    class Fruit(IntEnum):
+        apple = 0
+        banna = 1
+        orange = 2
+
+    class Cfg(BaseSettings):
+        fruit: Fruit
+
+    cfg = Cfg(_cli_parse_args=['--fruit', 'orange'])
+    assert cfg.model_dump() == {'fruit': Fruit.orange}
+
+    with pytest.raises(SystemExit):
+        Cfg(_cli_parse_args=['--fruit', 'lettuce'])
+
+
 def test_cli_annotation_exceptions(monkeypatch):
     class SubCmdAlt(BaseModel):
         pass
@@ -2586,6 +2604,8 @@ class Settings(BaseSettings):
         (Union[SimpleSettings, SettingWithIgnoreEmpty], 'JSON'),
         (Union[SimpleSettings, str, SettingWithIgnoreEmpty], '{JSON,str}'),
         (Union[str, SimpleSettings, SettingWithIgnoreEmpty], '{str,JSON}'),
+        (Annotated[SimpleSettings, 'annotation'], 'JSON'),
+        (DirectoryPath, 'Path'),
     ],
 )
 def test_cli_metavar_format(value, expected):