Explicit Configuration Parameter

Instead of using the @use_config() decorator, you can explicitly add config to your typer command. However, you must include is_eager=True.

Simple YAML Example

This simple example uses a --config option to load a configuration from a YAML file.

An example typer app:

simple_app.py

from typing_extensions import Annotated

import typer
from typer_config.callbacks import yaml_conf_callback  # other formats available (1)

app = typer.Typer()


@app.command()
def main(
    name: str,
    greeting: Annotated[str, typer.Option()],
    suffix: Annotated[str, typer.Option()] = "!",
    config: Annotated[
        str,
        typer.Option(
            callback=yaml_conf_callback,
            is_eager=True,  # THIS IS REALLY IMPORTANT (2)
        ),
    ] = "",
):
    # possibly do something with config
    typer.echo(f"{greeting}, {name}{suffix}")


if __name__ == "__main__":
    app()

1. This package also provides json_conf_callback, toml_conf_callback, and dotenv_conf_callback for those file formats.

2. You must use is_eager=True in the parameter definition because that will cause it to be processed first. If you don't use is_eager, then your parameter values will depend on the order in which they were processed (read: unpredictably).

With a config file:

config.yml

name: World
greeting: Hello
suffix: "!"

And invoked with python:

Terminal

$ python simple_app.py --config config.yml
Hello, World!

$ python simple_app.py --config config.yml Alice
Hello, Alice!

$ python simple_app.py --config config.yml --greeting Hi
Hi, World!