Schema Validation Example

This simple example uses a --config option to load a configuration from a YAML file and uses schema to validate the file before continuing.

An example typer app:

simple_app.py

from typing import Any, Dict
from typing_extensions import Annotated

from schema import Schema
import typer
from typer_config import yaml_loader, conf_callback_factory, use_config

schema = Schema({"arg1": str, "opt1": str, "opt2": str})


def validator_loader(param_value: str) -> Dict[str, Any]:
    conf = yaml_loader(param_value)
    conf = schema.validate(conf)  # raises an exception if not valid
    return conf


validator_callback = conf_callback_factory(validator_loader)

app = typer.Typer()


@app.command()
@use_config(validator_callback)
def main(
    arg1: str,
    opt1: Annotated[str, typer.Option()],
    opt2: Annotated[str, typer.Option()] = "hello",
):
    typer.echo(f"{opt1} {opt2} {arg1}")


if __name__ == "__main__":
    app()

With a config file:

config.yml

arg1: stuff
opt1: things
opt2: nothing

And invoked with python:

$ python simple_app.py --config config.yml
things nothing stuff

$ python simple_app.py --config config.yml others
things nothing others

$ python simple_app.py --config config.yml --opt1 people
people nothing stuff