Module flash 

Flash messages and redirects (18.35.0, #94): a message set on one response — usually a redirect after a form post — and shown on the next page, once.

use rust_web_server::app::App;
use rust_web_server::error::IntoResponse;
use rust_web_server::extract::FromRequest;
use rust_web_server::flash::{Flash, FlashLayer, Redirect};
use rust_web_server::response::{Response, STATUS_CODE_REASON_PHRASE};
use rust_web_server::test_client::TestClient;

let app = App::with_state(())
    .post("/posts", |_, _, _, _| Redirect::to("/posts").notice("Post saved").into_response())
    .get("/posts", |request, _, _, _| {
        let flash = Flash::from_request(request).unwrap();
        Response::text(STATUS_CODE_REASON_PHRASE.n200_ok, flash.notice().unwrap_or(""))
    })
    .wrap(FlashLayer::new());

let client = TestClient::new(app);
let saved = client.post("/posts").send();
assert_eq!(303, saved.status());

The messages travel in the rws_flash cookie (HttpOnly, SameSite=Lax, Path=/), percent-encoded: readable and changeable by the browser, so never put anything in a flash that the page trusts — templates escape it like any other text. FlashLayer removes the cookie from the browser after the request that carried it, unless the response sets a new flash. A flash cookie is capped at MAX_COOKIE_BYTES; messages past it are dropped.

Structs

Flash

The flash messages a request carried. A handler argument (FromRequest, never fails); empty when there are none.

FlashLayer

Removes the flash cookie after the request that carried it, unless the response sets a new flash. Wrap the app in it once: app.wrap(FlashLayer::new()).

FlashMessage

One message: its kind (notice, alert, or your own) and its text.

Redirect

A redirect, optionally with flash messages: 303 See Other by default (the method after a form post becomes GET).

Constants

COOKIE_NAME

The cookie flash messages travel in.

MAX_COOKIE_BYTES

The largest flash cookie value written; later messages are dropped.

Functions

set

Add a flash message to response (after any it already sets).