Applications with Rullst I · Lesson 03 / 14

Routes: an address and an intention

The same path can receive read and create requests.

Let's discover together

1
A request combines method, path, headers and sometimes a body. In src/routes.rs, GET /api/missions calls list and POST on that path calls create. The router chooses the handler; the handler applies rules and produces the response.
2
The root / serves HTML; /app.js and /style.css serve files embedded at compile time. /api/missions returns database JSON. There is no api/missions folder: a route is an access contract, not necessarily a disk file.
3
Open /healthz and /api/missions in the browser. Check status and Content-Type in the developer tools Network tab. /healthz confirms the process responds; it is not a complete persistence test. GET should read without creating missions.
4
Stop the server, add GET /about-lab with a short response and run again. include_str! embeds files; HTML, JS and CSS changes also need rebuilding. The kit does not include automatic reload.

Your application workbench

The kit includes a complete app to investigate and modify. The excerpt below explains this step; the editor contains the indicated file. Rullst Academy does not compile or run this server in your browser.

File to study and modify

src/routes.rs

.route("/api/missions", get(list).post(create))
.route("/healthz", get(health))

Extract the kit to a new folder and open a terminal beside Cargo.toml. Use Rust 1.96+; the first build may download dependencies and take time. Then open http://127.0.0.1:3010. Stop with Ctrl+C and run again after editing.

cargo test --locked
cargo run --locked

My files and GitHub

Download your draft and replace the indicated file in your extracted copy. The editor saves one file in this browser; your account saves assessments and XP. The ZIP excludes your edits. GitHub sends only the confirmed file; use Git manually for the whole app, excluding databases, backups and secrets.

Official links and next step

Rullst Core 12.1: routing

✦

YOUR MISSION

Relate method, path, handler and response without confusing a route with a file.

Take it with you

Draw the path of a read and a create. Add the introduction route and confirm that opening it three times does not change the list.

At your own pace

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Your path, step by step

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My code or notes

use crate::{
    store::Store,
    validation::{self, Completion, NewMission},
};
use rullst::{
    Router,
    response::{IntoResponse, Response},
    server::{Extension, Json, Path, StatusCode, get},
    web::axum::{
        extract::{DefaultBodyLimit, Request, rejection::JsonRejection},
        middleware::{Next, from_fn},
    },
};
use serde_json::json;

fn error(status: StatusCode, code: &str) -> Response {
    (status, Json(json!({"error": code}))).into_response()
}
fn unavailable() -> Response {
    // No submitted text, SQL, paths or credentials in browser errors or logs.
    eprintln!("mission-board: database operation failed");
    error(StatusCode::SERVICE_UNAVAILABLE, "storage_unavailable")
}

async fn list(Extension(store): Extension<Store>) -> Response {
    match store.list().await {
        Ok(items) => Json(items).into_response(),
        Err(_) => unavailable(),
    }
}
async fn create(
    Extension(store): Extension<Store>,
    input: Result<Json<NewMission>, JsonRejection>,
) -> Response {
    let Json(input) = match input {
        Ok(value) => value,
        Err(e) => return error(e.status(), "invalid_json"),
    };
    let input = match validation::validate(input) {
        Ok(value) => value,
        Err(code) => return error(StatusCode::UNPROCESSABLE_ENTITY, code),
    };
    match store.create(input).await {
        Ok(item) => (StatusCode::CREATED, Json(item)).into_response(),
        Err(_) => unavailable(),
    }
}
async fn complete(
    Extension(store): Extension<Store>,
    Path(id): Path<i64>,
    input: Result<Json<Completion>, JsonRejection>,
) -> Response {
    let Json(input) = match input {
        Ok(value) => value,
        Err(e) => return error(e.status(), "invalid_json"),
    };
    match store.complete(id, input.done).await {
        Ok(true) => StatusCode::NO_CONTENT.into_response(),
        Ok(false) => error(StatusCode::NOT_FOUND, "not_found"),
        Err(_) => unavailable(),
    }
}
#[derive(Clone)]
struct Origins(Vec<String>);

async fn boundary(
    Extension(origins): Extension<Origins>,
    request: Request,
    next: Next,
) -> Response {
    // A loopback exercise, not an authentication/authorization system.
    if request.method() != "GET" && request.method() != "HEAD" {
        if let Some(origin) = request.headers().get("origin") {
            if !origin
                .to_str()
                .is_ok_and(|value| origins.0.iter().any(|allowed| allowed == value))
            {
                return error(StatusCode::FORBIDDEN, "invalid_origin");
            }
        }
    }
    let mut response = next.run(request).await;
    response
        .headers_mut()
        .insert("cache-control", "no-store".parse().unwrap());
    response
        .headers_mut()
        .insert("x-content-type-options", "nosniff".parse().unwrap());
    response.headers_mut().insert("content-security-policy", "default-src 'none'; script-src 'self'; style-src 'self'; connect-src 'self'; base-uri 'none'; frame-ancestors 'none'; form-action 'self'".parse().unwrap());
    response
}

pub fn app(store: Store) -> Router {
    app_with_origins(store, &["http://127.0.0.1:3010", "http://localhost:3010"])
}

pub fn app_with_origins(store: Store, origins: &[&str]) -> Router {
    Router::new()
        .route(
            "/",
            get(|| async { rullst::response::Html(include_str!("../web/index.html")) }),
        )
        .route(
            "/app.js",
            get(|| async {
                (
                    [("content-type", "text/javascript; charset=utf-8")],
                    include_str!("../web/app.js"),
                )
            }),
        )
        .route(
            "/style.css",
            get(|| async {
                (
                    [("content-type", "text/css; charset=utf-8")],
                    include_str!("../web/style.css"),
                )
            }),
        )
        .route("/healthz", get(|| async { Json(json!({"status":"ok"})) }))
        .route("/api/missions", get(list).post(create))
        .route(
            "/api/missions/{id}/completion",
            rullst::web::axum::routing::put(complete),
        )
        .fallback(|| async { error(StatusCode::NOT_FOUND, "not_found") })
        .layer(DefaultBodyLimit::max(4096))
        .layer(from_fn(boundary))
        .layer(Extension(Origins(
            origins.iter().map(|v| (*v).into()).collect(),
        )))
        .layer(Extension(store))
}

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Routes: an address and an intention

Let's discover together

Your application workbench

File to study and modify

Official links and next step

Now it's your turn

Decide before running

Take it with you

My files and GitHub

Your file for this lesson

Save to my GitHub

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