how to use typer on class method __init__ with self argument, got this error: Error: Missing argument 'SELF'.

[fbenavides69]

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Example Code

import typer

app = typer.Typer()


class some:
    @app.command()
    def __init__(self, start_date: Optional[str] = None, stop_date: Optional[str] = None) -> None:
        self.start = start_date
        self.stop = stop_date

    def run():
        print(f"{self.start} - {self.stop}")

if __name__ == "__main__":
    dc = app.run(some())
    dc.run()

Description

Typer deals with the "self" argument in the class constructor "init" and does not know how to deal with that, please help!

Operating System

Windows

Operating System Details

No response

Typer Version

0.7.0

Python Version

Python 3.8.5

Additional Context

No response

[jonaslb]

I'm not sure using typer like that on an init method is actually supported. I think having your CLI be a simple method is really to be preferred. Try putting the CLI into its own method, and then call whatever program logic you have from there, like this for example:

import typer
from typing import Optional
from datetime import datetime

class Some:
    # your class impl
    pass

def main(start_date: Optional[datetime] = None, stop_date: Optional[datetime] = None):
    Some(start_date, stop_date).run()

if __name__ == "__main__":
    typer.run(main)

[kuykendall-ben]

You can totally use a constructor as a typer command. However, it's pretty confusing! I would recommend @jonaslb's approach above instead. But if you really want to... the trick is to decorate the class instead of the initializer:

from typing import Optional
import typer

app = typer.Typer()

@app.command()
class Some:
    def __init__(self, start_date: Optional[str] = None, stop_date: Optional[str] = None) -> None:
        self.start = start_date
        self.stop = stop_date
        self.run()

    def run(self):
        print(f"{self.start} - {self.stop}")

if __name__ == "__main__":
    app()

Then

$ /usr/bin/python3 main.py --start-date 2023-01-01 --stop-date 2023-12-31
2023-01-01 - 2023-12-31

However, your code as written has a few other problems. The biggest one to me is trying to use the return value of the typer entry point. You shouldn't run any code after calling app(). Make sure all the code you want to execute is inside your command.