Rust: Create editable CLI input

Question

To read user input in rust, we can do this:

use std::io;
let mut input = String::new();
print!("Edit username: ");
io::stdout().flush().ok();
io::stdin().readline(&mut input);

What I want is a way to create editable input text, like filling the stdin with some text that the user can edit. Something like this:

  stdout              stdin
     |                  |
Edit username: <existing username>

Answer 1

If you are OK with using an external crate, and you don't need the full terminal UI capabilities of something like tui (which depends on termion or crossterm), you can use rustyline.

use rustyline::{DefaultEditor, Result};

fn main() -> Result<()> {
    let mut rl = DefaultEditor::new()?;
    const DEFAULT_USERNAME: &str = "admin";
    let input = rl.readline_with_initial("Edit username: ", (DEFAULT_USERNAME, ""))?;
    println!("Your selected username: {input}");
    Ok(())
}

Credit to this answer (How do I enable editable user input for a Rust terminal application?)