How to Handle Request Validation in Rust (validator crate)

Use the validator crate by adding it to Cargo.toml and applying attribute macros to your struct fields to define validation rules.

[dependencies]
validator = "0.18"

use validator::Validate;

#[derive(Validate)]
struct User {
    #[validate(length(min = 3, max = 25), email)]
    email: String,
    #[validate(length(min = 8))]
    password: String,
}

fn main() {
    let user = User {
        email: "short@x.com".to_string(),
        password: "123".to_string(),
    };
    
    match user.validate() {
        Ok(_) => println!("Valid!"),
        Err(e) => println!("Validation failed: {e}"),
    }
}

The validator crate lets you define rules for your data directly on your code structures, like requiring a password to be long enough or an email to be real. When you run your program, it automatically checks if the data follows these rules before you use it. Think of it like a bouncer at a club checking IDs and dress codes before letting guests inside.