🐛 Ensure that Optional[list] values work correctly with callbacks

docs_src/options/callback/tutorial005.py

@@ -0,0 +1,27 @@
+from typing import List, Optional
+
+import typer
+
+
+def names_callback(ctx: typer.Context, param: typer.CallbackParam, value: str):
+    if ctx.resilient_parsing:
+        return
+    print(f"Validating param: {param.name}")
+    if value is None:
+        return value
+    if "Camila" not in value:
+        raise typer.BadParameter("Camila must be in the list")
+    return value
+
+
+def main(
+    names: Optional[List[str]] = typer.Option(None, "--name", callback=names_callback),
+):
+    if names is None:
+        print("No names provided")
+    else:
+        print("Hello {}".format(", ".join(names)))
+
+
+if __name__ == "__main__":
+    typer.run(main)

docs_src/options/callback/tutorial005_an.py

@@ -0,0 +1,30 @@
+from typing import List, Optional
+
+import typer
+from typing_extensions import Annotated
+
+
+def names_callback(ctx: typer.Context, param: typer.CallbackParam, value: str):
+    if ctx.resilient_parsing:
+        return
+    print(f"Validating param: {param.name}")
+    if value is None:
+        return value
+    if "Camila" not in value:
+        raise typer.BadParameter("Camila must be in the list")
+    return value
+
+
+def main(
+    names: Annotated[
+        Optional[List[str]], typer.Option("--name", callback=names_callback)
+    ] = None,
+):
+    if names is None:
+        print("No names provided")
+    else:
+        print("Hello {}".format(", ".join(names)))
+
+
+if __name__ == "__main__":
+    typer.run(main)

tests/test_tutorial/test_options/test_callback/test_tutorial005.py

@@ -0,0 +1,56 @@
+import os
+import subprocess
+import sys
+
+import typer
+from typer.testing import CliRunner
+
+from docs_src.options.callback import tutorial005 as mod
+
+runner = CliRunner()
+
+app = typer.Typer()
+app.command()(mod.main)
+
+
+def test_1():
+    result = runner.invoke(app, ["--name", "Camila", "--name", "Victor"])
+    assert result.exit_code == 0
+    assert "Validating param: name" in result.output
+    assert "Hello Camila, Victor" in result.output
+
+
+def test_2():
+    result = runner.invoke(app, ["--name", "rick", "--name", "Victor"])
+    assert result.exit_code != 0
+    assert "Invalid value for '--name': Camila must be in the list" in result.output
+
+
+def test_3():
+    result = runner.invoke(app, [])
+    assert result.exit_code == 0
+    assert "No names provided" in result.output
+
+
+def test_script():
+    result = subprocess.run(
+        [sys.executable, "-m", "coverage", "run", mod.__file__, "--help"],
+        capture_output=True,
+        encoding="utf-8",
+    )
+    assert "Usage" in result.stdout
+
+
+def test_completion():
+    result = subprocess.run(
+        [sys.executable, "-m", "coverage", "run", mod.__file__, " "],
+        capture_output=True,
+        encoding="utf-8",
+        env={
+            **os.environ,
+            "_TUTORIAL005.PY_COMPLETE": "complete_bash",
+            "COMP_WORDS": "tutorial005.py --",
+            "COMP_CWORD": "1",
+        },
+    )
+    assert "--name" in result.stdout

tests/test_tutorial/test_options/test_callback/test_tutorial005_an.py

@@ -0,0 +1,56 @@
+import os
+import subprocess
+import sys
+
+import typer
+from typer.testing import CliRunner
+
+from docs_src.options.callback import tutorial005_an as mod
+
+runner = CliRunner()
+
+app = typer.Typer()
+app.command()(mod.main)
+
+
+def test_1():
+    result = runner.invoke(app, ["--name", "Camila", "--name", "Victor"])
+    assert result.exit_code == 0
+    assert "Validating param: name" in result.output
+    assert "Hello Camila, Victor" in result.output
+
+
+def test_2():
+    result = runner.invoke(app, ["--name", "rick", "--name", "Victor"])
+    assert result.exit_code != 0
+    assert "Invalid value for '--name': Camila must be in the list" in result.output
+
+
+def test_3():
+    result = runner.invoke(app, [])
+    assert result.exit_code == 0
+    assert "No names provided" in result.output
+
+
+def test_script():
+    result = subprocess.run(
+        [sys.executable, "-m", "coverage", "run", mod.__file__, "--help"],
+        capture_output=True,
+        encoding="utf-8",
+    )
+    assert "Usage" in result.stdout
+
+
+def test_completion():
+    result = subprocess.run(
+        [sys.executable, "-m", "coverage", "run", mod.__file__, " "],
+        capture_output=True,
+        encoding="utf-8",
+        env={
+            **os.environ,
+            "_TUTORIAL005_AN.PY_COMPLETE": "complete_bash",
+            "COMP_WORDS": "tutorial005_an.py --",
+            "COMP_CWORD": "1",
+        },
+    )
+    assert "--name" in result.stdout

typer/main.py

@@ -651,7 +651,7 @@ def generate_list_convertor(
     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:
+        if default_value is None and (value is None or len(value) == 0):
             return None
         return [convertor(v) if convertor else v for v in value]