Usage in Handlers

Pattern with Redirect (Flash Messages)

pub async fn submit_signup(
    mut request: Request,
    Prisme(mut form): Prisme<RegisterForm>,
) -> AppResult<Response> {
    if request.is_post() {
        if form.is_valid().await {
            let user = form.save(&request.engine.db).await.map_err(|err| {
                form.get_form_mut().database_error(&err);
                AppError::from(err)
            })?;

            // ✅ Flash message → displayed after redirect
            success!(request.notices => format!(
                "Welcome {}, your account has been created!",
                user.username
            ));
            return Ok(Redirect::to("/").into_response());
        }

        // ❌ Validation failed → immediate message (no redirect)
        context_update!(request => {
            "title" => "Validation error",
            "signup_form" => &form,
            "messages" => flash_now!(error => "Please fix the errors"),
        });
        return request.render("signup_form.html");
    }

    // GET → display form
    context_update!(request => {
        "title" => "Sign up",
        "signup_form" => &form,
    });
    request.render("signup_form.html")
}

pub async fn about(mut request: Request) -> AppResult<Response> {
    success!(request.notices => "This is a success message.");
    info!(request.notices => "This is an informational message.");
    warning!(request.notices => "This is a warning message.");
    error!(request.notices => "This is an error message.");

    context_update!(request => {
        "title" => "About",
    });
    request.render("about/about.html")
}

Flash messages stored in the session are automatically consumed upon display:

1. POST /signup
   → success!("Welcome!")
   → Redirect::to("/")

2. GET /
   → Messages read from session
   → Displayed in template
   → Removed from session

3. GET / (reload)
   → No messages (already consumed)