adding-cli-command

Templates and workflow for adding or updating Typer CLI commands.

<cli_app> refers to the name of your CLI application (e.g., task, myapp, todo).

Workflow

1. Identify command type (single command, command group, or destructive)
2. Create file in src/<cli_app>/commands/<command>.py
3. Use appropriate template below
4. Register in src/<cli_app>/commands/__init__.py

Template A: Single Command

For commands taking arguments directly (<cli_app> add "item").

import typer
from typing import Annotated

from <cli_app>.storage import add_task
from <cli_app>.display import display
from <cli_app>.constants import EXIT_INVALID_INPUT

app = typer.Typer()


@app.command()
def add(
    title: Annotated[str, typer.Argument(help="task title")],
    priority: Annotated[str, typer.Option("--priority", "-p", help="priority level")] = "low",
):
    """Add a new task."""
    if not title.strip():
        display.error("Title cannot be empty")
        raise typer.Exit(EXIT_INVALID_INPUT)

    task = add_task(title=title, priority=priority)
    display.success(f"Added '{task.title}'")

Template B: Command Group

For commands with subcommands (<cli_app> db migrate, <cli_app> db status).

import typer

from <cli_app>.storage import storage
from <cli_app>.display import display

app = typer.Typer(help="Database operations.")


@app.command()
def migrate():
    """Run database migrations."""
    storage.migrate()
    display.success("Migrations complete")


@app.command()
def status():
    """Show database status."""
    info = storage.get_status()
    display.info(f"Version: {info.version}")

Template C: Destructive Command

For deletion with confirmation.

import typer
from typing import Annotated

from <cli_app>.storage import get_task, delete_task
from <cli_app>.display import display
from <cli_app>.constants import EXIT_ERROR

app = typer.Typer()


@app.command()
def clear(
    task_id: Annotated[int, typer.Argument(help="task ID to delete")],
    force: Annotated[bool, typer.Option("--force", "-f", help="skip confirmation")] = False,
):
    """Delete a task permanently."""
    task = get_task(task_id)
    if not task:
        display.error(f"Task {task_id} not found")
        raise typer.Exit(EXIT_ERROR)

    if not force:
        confirm = typer.confirm(f"Delete '{task.title}'?", default=False)
        if not confirm:
            display.info("Cancelled")
            raise typer.Abort()

    delete_task(task_id)
    display.success(f"Deleted '{task.title}'")

Registration

Register in commands/__init__.py:

import typer

from .add import app as add_app
from .clear import app as clear_app

app = typer.Typer(help="<cli_app> CLI.", no_args_is_help=True)

# Single commands - add WITHOUT name
app.add_typer(add_app)
app.add_typer(clear_app)

# Command groups - add WITH name
# app.add_typer(db_app, name="db")

Conventions

| Rule | Example | |------|---------| | Arguments | Annotated[str, typer.Argument(help="...")] | | Options | Annotated[str, typer.Option("--name", "-n", help="...")] | | Docstrings | Imperative mood, < 60 chars | | Output | Always via display module | | Exit codes | 0=success, 1=error, 2=invalid | | Destructive | Must have --force flag, default=False confirmation |