Salvo is an extremely simple and powerful Rust web backend framework. Only basic Rust knowledge is required to develop backend services.

salvo-flash

Flash messages middleware for the Salvo web framework. Flash messages are temporary notifications that persist across a single redirect, commonly used to display success, error, or info messages after form submissions.

Features

• Multiple storage backends: Cookie-based or session-based storage
• Message levels: Debug, Info, Success, Warning, and Error severity levels
• Level filtering: Filter messages by minimum severity level
• Easy integration: Simple API for setting and retrieving flash messages
• Automatic cleanup: Messages are automatically cleared after being read

How It Works

1. A handler sets flash messages before redirecting
2. The middleware stores them (in cookies or session)
3. On the next request, the messages are available and then cleared

Storage Options

Installation

This is an official crate, so you can enable it in Cargo.toml:

salvo = { version = "*", features = ["flash"] }

Quick Start

use salvo::prelude::*;
use salvo::flash::{FlashDepotExt, CookieStore};

#[handler]
async fn submit_form(depot: &mut Depot, res: &mut Response) {
    // Set flash message before redirect
    depot.outgoing_flash_mut().success("Form submitted successfully!");
    res.render(Redirect::other("/result"));
}

#[handler]
async fn show_result(depot: &mut Depot, res: &mut Response) {
    if let Some(flash) = depot.incoming_flash() {
        for msg in flash.iter() {
            println!("{}: {}", msg.level, msg.value);
        }
    }
    res.render("Result page");
}

#[tokio::main]
async fn main() {
    let router = Router::new()
        .hoop(CookieStore::new().into_handler())
        .push(Router::with_path("submit").post(submit_form))
        .push(Router::with_path("result").get(show_result));

    let acceptor = TcpListener::new("0.0.0.0:8698").bind().await;
    Server::new(acceptor).serve(router).await;
}

Documentation & Resources

• API Documentation
• Example Projects

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⚠️ License

Salvo is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0).

• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT).