Salvo Basic Application Setup

This skill helps create basic Salvo web applications with proper structure and best practices.

Core Concepts

Handler

Handlers process HTTP requests. Use the #[handler] macro on async functions:

use salvo::prelude::*;

#[handler]
async fn hello() -> &'static str {
    "Hello World"
}

#[handler]
async fn greet(req: &mut Request) -> String {
    let name = req.query::<String>("name").unwrap_or("World".to_string());
    format!("Hello, {}!", name)
}

Handler parameters can be in any order and are all optional:

• req: &mut Request – HTTP request object
• res: &mut Response – HTTP response object
• depot: &mut Depot – Request-scoped data storage
• ctrl: &mut FlowCtrl – Flow control for middleware

Router

Routers define URL paths and attach handlers:

use salvo::prelude::*;

let router = Router::new()
    .get(hello)
    .push(Router::with_path("greet").get(greet));

Server Setup

Basic server configuration:

use salvo::prelude::*;

#[handler]
async fn hello() -> &'static str {
    "Hello World"
}

#[tokio::main]
async fn main() {
    let router = Router::new().get(hello);
    let acceptor = TcpListener::new("0.0.0.0:8080").bind().await;
    Server::new(acceptor).serve(router).await;
}

Response Types

Returning Different Types

Handlers can return any type implementing Writer or Scribe:

use salvo::prelude::*;

#[handler]
async fn json_response() -> Json<serde_json::Value> {
    Json(serde_json::json!({"status": "ok"}))
}

#[handler]
async fn text_response() -> &'static str {
    "Plain text response"
}

#[handler]
async fn html_response(res: &mut Response) {
    res.render(salvo::writing::Html("<h1>Hello</h1>"));
}

#[handler]
async fn status_response() -> StatusCode {
    StatusCode::NO_CONTENT
}

#[handler]
async fn redirect_response(res: &mut Response) {
    res.render(salvo::writing::Redirect::found("https://example.com"));
}

Rendering JSON

use salvo::prelude::*;
use serde::Serialize;

#[derive(Serialize)]
struct User {
    name: String,
    age: u8,
}

#[handler]
async fn get_user() -> Json<User> {
    Json(User {
        name: "Alice".to_string(),
        age: 30,
    })
}

Error Handling

Return Result<T, E> where both implement Writer:

use salvo::prelude::*;

#[handler]
async fn may_fail() -> Result<Json<Data>, StatusError> {
    let data = fetch_data().await.map_err(|_| StatusError::internal_server_error())?;
    Ok(Json(data))
}

Request Object

Common Request Methods

#[handler]
async fn handle_request(req: &mut Request) -> String {
    // Get request method
    let method = req.method();

    // Get request URI
    let uri = req.uri();

    // Get header value
    if let Some(content_type) = req.header::<String>("Content-Type") {
        println!("Content-Type: {}", content_type);
    }

    // Get query parameter
    let name = req.query::<String>("name").unwrap_or_default();

    // Get path parameter (requires route like /users/{id})
    let id = req.param::<i64>("id").unwrap();

    // Parse JSON body
    let body: UserData = req.parse_json().await.unwrap();

    format!("Processed request")
}

Response Object

Common Response Methods

use salvo::prelude::*;

#[handler]
async fn handle_response(res: &mut Response) {
    // Set status code
    res.status_code(StatusCode::CREATED);

    // Set response header
    res.headers_mut().insert("X-Custom-Header", "value".parse().unwrap());

    // Render text response
    res.render("Hello, World!");
}

Dependencies

Add to Cargo.toml:

[dependencies]
salvo = "0.89.0"
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
serde = { version = "1", features = ["derive"] }
serde_json = "1"

Best Practices

1. Use #[handler] macro for all handlers
2. Keep handlers focused on single responsibility
3. Use appropriate return types (Json, Text, StatusCode)
4. Handle errors with Result types
5. Use TcpListener for basic HTTP servers
6. Extract common logic into middleware using hoop()