Add environment parsing support for enums.

pydantic_settings/main.py

@@ -28,6 +28,7 @@ class SettingsConfigDict(ConfigDict, total=False):
     env_ignore_empty: bool
     env_nested_delimiter: str | None
     env_parse_none_str: str | None
+    env_parse_enums: bool | None
     secrets_dir: str | Path | None
     json_file: PathType | None
     json_file_encoding: str | None
@@ -65,6 +66,7 @@ class BaseSettings(BaseModel):
         _env_nested_delimiter: The nested env values delimiter. Defaults to `None`.
         _env_parse_none_str: The env string value that should be parsed (e.g. "null", "void", "None", etc.)
             into `None` type(None). Defaults to `None` type(None), which means no parsing should occur.
+        _env_parse_enums: Parse enum field names to values. Defaults to `None.`, which means no parsing should occur.
         _secrets_dir: The secret files directory. Defaults to `None`.
     """
 
@@ -77,6 +79,7 @@ def __init__(
         _env_ignore_empty: bool | None = None,
         _env_nested_delimiter: str | None = None,
         _env_parse_none_str: str | None = None,
+        _env_parse_enums: bool | None = None,
         _secrets_dir: str | Path | None = None,
         **values: Any,
     ) -> None:
@@ -91,6 +94,7 @@ def __init__(
                 _env_ignore_empty=_env_ignore_empty,
                 _env_nested_delimiter=_env_nested_delimiter,
                 _env_parse_none_str=_env_parse_none_str,
+                _env_parse_enums=_env_parse_enums,
                 _secrets_dir=_secrets_dir,
             )
         )
@@ -129,6 +133,7 @@ def _settings_build_values(
         _env_ignore_empty: bool | None = None,
         _env_nested_delimiter: str | None = None,
         _env_parse_none_str: str | None = None,
+        _env_parse_enums: bool | None = None,
         _secrets_dir: str | Path | None = None,
     ) -> dict[str, Any]:
         # Determine settings config values
@@ -149,6 +154,7 @@ def _settings_build_values(
         env_parse_none_str = (
             _env_parse_none_str if _env_parse_none_str is not None else self.model_config.get('env_parse_none_str')
         )
+        env_parse_enums = _env_parse_enums if _env_parse_enums is not None else self.model_config.get('env_parse_enums')
         secrets_dir = _secrets_dir if _secrets_dir is not None else self.model_config.get('secrets_dir')
 
         # Configure built-in sources
@@ -160,6 +166,7 @@ def _settings_build_values(
             env_nested_delimiter=env_nested_delimiter,
             env_ignore_empty=env_ignore_empty,
             env_parse_none_str=env_parse_none_str,
+            env_parse_enums=env_parse_enums,
         )
         dotenv_settings = DotEnvSettingsSource(
             self.__class__,
@@ -170,6 +177,7 @@ def _settings_build_values(
             env_nested_delimiter=env_nested_delimiter,
             env_ignore_empty=env_ignore_empty,
             env_parse_none_str=env_parse_none_str,
+            env_parse_enums=env_parse_enums,
         )
 
         file_secret_settings = SecretsSettingsSource(
@@ -201,6 +209,7 @@ def _settings_build_values(
         env_ignore_empty=False,
         env_nested_delimiter=None,
         env_parse_none_str=None,
+        env_parse_enums=None,
         json_file=None,
         json_file_encoding=None,
         yaml_file=None,

pydantic_settings/sources.py

@@ -7,6 +7,7 @@
 from abc import ABC, abstractmethod
 from collections import deque
 from dataclasses import is_dataclass
+from enum import Enum
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, List, Mapping, Sequence, Tuple, Union, cast
 
@@ -179,6 +180,7 @@ def __init__(
         env_prefix: str | None = None,
         env_ignore_empty: bool | None = None,
         env_parse_none_str: str | None = None,
+        env_parse_enums: bool | None = None,
     ) -> None:
         super().__init__(settings_cls)
         self.case_sensitive = case_sensitive if case_sensitive is not None else self.config.get('case_sensitive', False)
@@ -189,6 +191,7 @@ def __init__(
         self.env_parse_none_str = (
             env_parse_none_str if env_parse_none_str is not None else self.config.get('env_parse_none_str')
         )
+        self.env_parse_enums = env_parse_enums if env_parse_enums is not None else self.config.get('env_parse_enums')
 
     def _apply_case_sensitive(self, value: str) -> str:
         return value.lower() if not self.case_sensitive else value
@@ -357,8 +360,11 @@ def __init__(
         env_prefix: str | None = None,
         env_ignore_empty: bool | None = None,
         env_parse_none_str: str | None = None,
+        env_parse_enums: bool | None = None,
     ) -> None:
-        super().__init__(settings_cls, case_sensitive, env_prefix, env_ignore_empty, env_parse_none_str)
+        super().__init__(
+            settings_cls, case_sensitive, env_prefix, env_ignore_empty, env_parse_none_str, env_parse_enums
+        )
         self.secrets_dir = secrets_dir if secrets_dir is not None else self.config.get('secrets_dir')
 
     def __call__(self) -> dict[str, Any]:
@@ -447,8 +453,11 @@ def __init__(
         env_nested_delimiter: str | None = None,
         env_ignore_empty: bool | None = None,
         env_parse_none_str: str | None = None,
+        env_parse_enums: bool | None = None,
     ) -> None:
-        super().__init__(settings_cls, case_sensitive, env_prefix, env_ignore_empty, env_parse_none_str)
+        super().__init__(
+            settings_cls, case_sensitive, env_prefix, env_ignore_empty, env_parse_none_str, env_parse_enums
+        )
         self.env_nested_delimiter = (
             env_nested_delimiter if env_nested_delimiter is not None else self.config.get('env_nested_delimiter')
         )
@@ -498,6 +507,10 @@ def prepare_field_value(self, field_name: str, field: FieldInfo, value: Any, val
             ValuesError: When There is an error in deserializing value for complex field.
         """
         is_complex, allow_parse_failure = self._field_is_complex(field)
+        if self.env_parse_enums and lenient_issubclass(field.annotation, Enum):
+            if value in tuple(val.name for val in field.annotation):  # type: ignore
+                value = field.annotation[value]  # type: ignore
+
         if is_complex or value_is_complex:
             if value is None:
                 # field is complex but no value found so far, try explode_env_vars
@@ -645,13 +658,20 @@ def __init__(
         env_nested_delimiter: str | None = None,
         env_ignore_empty: bool | None = None,
         env_parse_none_str: str | None = None,
+        env_parse_enums: bool | None = None,
     ) -> None:
         self.env_file = env_file if env_file != ENV_FILE_SENTINEL else settings_cls.model_config.get('env_file')
         self.env_file_encoding = (
             env_file_encoding if env_file_encoding is not None else settings_cls.model_config.get('env_file_encoding')
         )
         super().__init__(
-            settings_cls, case_sensitive, env_prefix, env_nested_delimiter, env_ignore_empty, env_parse_none_str
+            settings_cls,
+            case_sensitive,
+            env_prefix,
+            env_nested_delimiter,
+            env_ignore_empty,
+            env_parse_none_str,
+            env_parse_enums,
         )
 
     def _load_env_vars(self) -> Mapping[str, str | None]:

tests/test_settings.py

@@ -4,6 +4,7 @@
 import sys
 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
 
@@ -1853,6 +1854,40 @@ class Settings(BaseSettings):
     ]
 
 
+def test_env_parse_enums(env):
+    class FruitsEnum(IntEnum):
+        pear = 0
+        kiwi = 1
+        lime = 2
+
+    class Settings(BaseSettings):
+        fruit: FruitsEnum
+
+    with pytest.raises(ValidationError) as exc_info:
+        env.set('FRUIT', 'kiwi')
+        s = Settings()
+    assert exc_info.value.errors(include_url=False) == [
+        {
+            'type': 'int_parsing',
+            'loc': ('fruit',),
+            'msg': 'Input should be a valid integer, unable to parse string as an integer',
+            'input': 'kiwi',
+        }
+    ]
+
+    env.set('FRUIT', str(FruitsEnum.lime.value))
+    s = Settings()
+    assert s.fruit == FruitsEnum.lime
+
+    env.set('FRUIT', 'kiwi')
+    s = Settings(_env_parse_enums=True)
+    assert s.fruit == FruitsEnum.kiwi
+
+    env.set('FRUIT', str(FruitsEnum.lime.value))
+    s = Settings(_env_parse_enums=True)
+    assert s.fruit == FruitsEnum.lime
+
+
 def test_env_parse_none_str(env):
     env.set('x', 'null')
     env.set('y', 'y_override')