♻️ Add custom TyperChoice type for compatibility with Click 8.2.0, keeping the same behavior of enums

tiangolo · tiangolo · commit 3b8f9bc7436e · 2025-05-26T15:30:39.000+02:00
diff --git a/typer/_types.py b/typer/_types.py
@@ -0,0 +1,27 @@
+from enum import Enum
+from typing import Generic, TypeVar, Union
+
+import click
+
+ParamTypeValue = TypeVar("ParamTypeValue")
+
+
+class TyperChoice(click.Choice, Generic[ParamTypeValue]):  # type: ignore[type-arg]
+    def normalize_choice(
+        self, choice: ParamTypeValue, ctx: Union[click.Context, None]
+    ) -> str:
+        # Click 8.2.0 added a new method `normalize_choice` to the `Choice` class
+        # to support enums, but it uses the enum names, while Typer has always used the
+        # enum values.
+        # This class overrides that method to maintain the previous behavior.
+        # In Click:
+        # normed_value = choice.name if isinstance(choice, Enum) else str(choice)
+        normed_value = choice.value if isinstance(choice, Enum) else str(choice)
+
+        if ctx is not None and ctx.token_normalize_func is not None:
+            normed_value = ctx.token_normalize_func(normed_value)
+
+        if not self.case_sensitive:
+            normed_value = normed_value.casefold()
+
+        return normed_value
diff --git a/typer/main.py b/typer/main.py
@@ -15,6 +15,7 @@
 from uuid import UUID
 
 import click
+from typer._types import TyperChoice
 
 from ._typing import get_args, get_origin, is_union
 from .completion import get_completion_inspect_parameters
@@ -787,7 +788,12 @@ def get_click_type(
             atomic=parameter_info.atomic,
         )
     elif lenient_issubclass(annotation, Enum):
-        return click.Choice(
+        # The custom TyperChoice is only needed for Click < 8.2.0, to parse the
+        # command line values matching them to the enum values. Click 8.2.0 added
+        # support for enum values but reading enum names.
+        # Passing here the list of enum values (instead of just the enum) accounts for
+        # Click < 8.2.0.
+        return TyperChoice(
             [item.value for item in annotation],
             case_sensitive=parameter_info.case_sensitive,
         )
