Python Typer User Prompting Guide

Python Typer makes CLI app development easy. One key feature is user prompting. This guide covers prompts, confirmations, and hidden inputs.

Getting Started with Typer Prompts

Typer's prompt function asks users for input. It's simple and customizable. Here's a basic example:

import typer

app = typer.Typer()

@app.command()
def greet():
    name = typer.prompt("What's your name?")
    typer.echo(f"Hello, {name}!")

if __name__ == "__main__":
    app()

$ python app.py
What's your name? John
Hello, John!

The prompt function waits for user input. It's perfect for simple data collection.

Adding Default Values

You can provide default values in prompts. This improves user experience. The default appears in brackets.

@app.command()
def greet():
    name = typer.prompt("What's your name?", default="Guest")
    typer.echo(f"Hello, {name}!")

$ python app.py
What's your name? [Guest]: 
Hello, Guest!

Users can press Enter to accept defaults. This saves time for common cases.

Confirmation Prompts

Typer's confirm function asks yes/no questions. It returns True or False. Great for critical actions.

@app.command()
def delete_file():
    if typer.confirm("Are you sure you want to delete?"):
        typer.echo("File deleted!")
    else:
        typer.echo("Operation cancelled.")

$ python app.py
Are you sure you want to delete? [y/N]: y
File deleted!

Confirmation prompts prevent accidental actions. Always use them for destructive operations.

Hidden Input for Sensitive Data

Use typer.secret for passwords or API keys. It hides input while typing.

@app.command()
def login():
    password = typer.prompt("Enter password", hide_input=True)
    typer.echo("Login attempt received.")

$ python app.py
Enter password: ********
Login attempt received.

For better security, use typer.secret instead. It prevents password display in logs.

Advanced Prompt Customization

Typer prompts support type validation. Add type parameter for automatic conversion.

@app.command()
def calculate():
    age = typer.prompt("Your age", type=int)
    typer.echo(f"In 10 years you'll be {age + 10}")

This ensures users enter valid numbers. Typer handles conversion automatically.

Combining with Other Typer Features

Prompts work well with subcommands and type hints. They create interactive CLI apps.

For complex apps, consider multiple commands. Each can have its own prompts.

Error Handling in Prompts

Typer automatically handles input errors. For custom validation, use loops or decorators.

@app.command()
def get_age():
    while True:
        age = typer.prompt("Age (18+)", type=int)
        if age >= 18:
            break
        typer.echo("Must be 18 or older!")
    typer.echo(f"Accepted age: {age}")

This ensures users enter valid ages. The prompt repeats until valid input.

Conclusion

Typer's prompting features make CLI apps interactive. Use prompt for input, confirm for yes/no, and secret for sensitive data.

Combine these with other Typer features for powerful apps. Remember to validate input and provide defaults.

For installation help, see our Typer installation guide. Start building interactive CLI apps today!