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Actix-web Rust web framework. Covers routing, extractors, middleware, state management, and WebSocket. Use for high-performance Rust APIs. USE WHEN: user mentions "actix-web", "actix", "rust web framework", "rust api", asks about "rust async web", "actix middleware", "actix extractors", "rust websocket", "high performance rust api" DO NOT USE FOR: Axum projects - use `axum` instead, Rocket projects - use `rocket` instead, Warp projects - use `warp` instead, non-Rust backends
npx skill4agent add claude-dev-suite/claude-dev-suite actix-webFull Reference: See advanced.md for custom timing middleware, authentication middleware, custom error types, WebSocket actors, and graceful shutdown patterns.
Deep Knowledge: Usewith technology:mcp__documentation__fetch_docsfor comprehensive documentation.actix-web
# Cargo.toml
[dependencies]
actix-web = "4"
actix-rt = "2"
serde = { version = "1", features = ["derive"] }
serde_json = "1"
tokio = { version = "1", features = ["full"] }use actix_web::{web, App, HttpServer, HttpResponse, Responder};
async fn hello() -> impl Responder {
HttpResponse::Ok().body("Hello, World!")
}
#[actix_web::main]
async fn main() -> std::io::Result<()> {
HttpServer::new(|| {
App::new()
.route("/", web::get().to(hello))
})
.bind("127.0.0.1:8080")?
.run()
.await
}use actix_web::{get, post, web, HttpResponse, Responder};
#[get("/users/{id}")]
async fn get_user(path: web::Path<u32>) -> impl Responder {
let id = path.into_inner();
HttpResponse::Ok().json(serde_json::json!({ "id": id }))
}
#[post("/users")]
async fn create_user(body: web::Json<CreateUser>) -> impl Responder {
HttpResponse::Created().json(body.into_inner())
}
// Register with App
App::new()
.service(get_user)
.service(create_user)| Extractor | Purpose |
|---|---|
| URL path parameters |
| Query string |
| JSON body |
| Form data |
| Application state |
struct AppState {
db_pool: Pool<Postgres>,
}
#[get("/users")]
async fn list_users(data: web::Data<AppState>) -> impl Responder {
let users = sqlx::query_as!(User, "SELECT * FROM users")
.fetch_all(&data.db_pool)
.await?;
HttpResponse::Ok().json(users)
}
HttpServer::new(move || {
App::new()
.app_data(web::Data::new(state.clone()))
.service(list_users)
})use actix_web::middleware::{Logger, Compress, NormalizePath};
App::new()
.wrap(Logger::default())
.wrap(Compress::default())
.wrap(NormalizePath::trim())#[get("/health")]
async fn health() -> impl Responder {
HttpResponse::Ok().json(serde_json::json!({ "status": "healthy" }))
}
#[get("/ready")]
async fn ready(data: web::Data<AppState>) -> impl Responder {
match data.db_pool.acquire().await {
Ok(_) => HttpResponse::Ok().json(serde_json::json!({
"status": "ready",
"database": "connected"
})),
Err(_) => HttpResponse::ServiceUnavailable().json(serde_json::json!({
"status": "not ready"
})),
}
}| Anti-Pattern | Why It's Bad | Solution |
|---|---|---|
| Performance overhead | Use |
| Blocking I/O in async handlers | Blocks executor threads | Use |
| Not using extractors | Manual parsing is error-prone | Use |
Missing | Manual runtime setup | Use macro for simple setup |
| Global mutable state | Data races | Use |
| No custom error types | Generic error messages | Implement |
| Problem | Diagnosis | Fix |
|---|---|---|
| "Cannot move out of borrowed content" | Ownership issue | Clone data or use |
| Handler not found (404) | Route not registered | Check |
| JSON parsing fails | Wrong content-type | Ensure client sends |
| Slow performance | Blocking I/O | Wrap blocking code in |
| WebSocket connection closes | Missing ping/pong | Implement heartbeat mechanism |
| State not accessible | Not added to app | Use |