Python script optional parameters and ui generation

[ilazarte]

How do I define an optional parameter for Python scripts? The form I prefer:

def foo(first_name: str = None):
    return f'Hello world from {first_name}'

doesn't appear to be recognized by the script parser correctly and shows red squiggles. I'm running the latest I assume (self host setup script)

edit: for reference I also tried Optional[str] from the typing module. It does make it optional but then requires quotes around the string in the input box which I find weird, it should understand it as either completely none, or a valid str. I did notice the ui thinks it's an object after using the Optional form.

[ghost]

This seems to work now (although I don't know about the web editor).

My version at this time: v1.349.1

Using wmill script generate-metadata brings up a field that is not required as expected.

Using typing.Optional completely fails here:

$ wmill script generate-metadata f/transform/aggregate-data.py 
Generating metadata for f/transform/aggregate-data.py
Script f/transform/aggregate-data.py invalid, it cannot be parsed to infer schema.
^C

^^ note that it just hangs there and I needed to interrupt it.

[rubenfiszel]

@enote-kane could you make an issue for both the hanging and for us supporting Optional, we should be able to do those

[ghost]

@rubenfiszel Turned out that it was my fault, since I had a parameter with a default value before the optional, so like this:

def main(required: str, with_def: str = "test", opt: Optional[str]):
    print("All OK")

That will not work (of course), since Python itself will complain about that definition (parameter opt has no default, hence will refuse to parse):

>>> def main(required: str, with_def: str = "test", opt: Optional[str]):
  File "<stdin>", line 1
    def main(required: str, with_def: str = "test", opt: Optional[str]):
                                                    ^^^^^^^^^^^^^^^^^^
SyntaxError: parameter without a default follows parameter with a default

Created #3954 for supporting Optional.