🐛 Fix default value of None for CLI Parameters when the type is list | None and the default value is None

docs/tutorial/multiple-values/multiple-options.md

@@ -26,9 +26,10 @@ Check it:
 <div class="termy">
 
 ```console
+// The default value is 'None'
 $ python main.py
 
-No provided users
+No provided users (raw input = None)
 Aborted!
 
 // Now pass a user

docs_src/multiple_values/multiple_options/tutorial001.py

@@ -5,7 +5,7 @@
 
 def main(user: Optional[List[str]] = typer.Option(None)):
     if not user:
-        print("No provided users")
+        print(f"No provided users (raw input = {user})")
         raise typer.Abort()
     for u in user:
         print(f"Processing user: {u}")

docs_src/multiple_values/multiple_options/tutorial001_an.py

@@ -6,7 +6,7 @@
 
 def main(user: Annotated[Optional[List[str]], typer.Option()] = None):
     if not user:
-        print("No provided users")
+        print(f"No provided users (raw input = {user})")
         raise typer.Abort()
     for u in user:
         print(f"Processing user: {u}")

tests/test_tutorial/test_multiple_values/test_multiple_options/test_tutorial001.py

@@ -15,6 +15,7 @@ def test_main():
     result = runner.invoke(app)
     assert result.exit_code != 0
     assert "No provided users" in result.output
+    assert "raw input = None" in result.output
     assert "Aborted" in result.output
 
 

tests/test_tutorial/test_multiple_values/test_multiple_options/test_tutorial001_an.py

@@ -15,6 +15,7 @@ def test_main():
     result = runner.invoke(app)
     assert result.exit_code != 0
     assert "No provided users" in result.output
+    assert "raw input = None" in result.output
     assert "Aborted" in result.output
 
 

typer/main.py

@@ -631,9 +631,11 @@ def convertor(value: Any) -> Any:
 
 
 def generate_list_convertor(
-    convertor: Optional[Callable[[Any], Any]]
-) -> Callable[[Sequence[Any]], List[Any]]:
-    def internal_convertor(value: Sequence[Any]) -> List[Any]:
+    convertor: Optional[Callable[[Any], Any]], default_value: Optional[Any]
+) -> Callable[[Sequence[Any]], Optional[List[Any]]]:
+    def internal_convertor(value: Sequence[Any]) -> Optional[List[Any]]:
+        if default_value is None and len(value) == 0:
+            return None
         return [convertor(v) if convertor else v for v in value]
 
     return internal_convertor
@@ -852,7 +854,9 @@ def get_click_param(
         )
     convertor = determine_type_convertor(main_type)
     if is_list:
-        convertor = generate_list_convertor(convertor)
+        convertor = generate_list_convertor(
+            convertor=convertor, default_value=default_value
+        )
     if is_tuple:
         convertor = generate_tuple_convertor(main_type.__args__)
     if isinstance(parameter_info, OptionInfo):