Using Flash for login error message.

src/main.rs

@@ -26,7 +26,14 @@ use num::BigUint;
 use openssl::rsa::Rsa;
 
 use ldap3::{ LdapConn, Scope, SearchEntry };
-use rocket::request::Form;
+use rocket::request::{
+    FlashMessage,
+    Form,
+};
+use rocket::response::{
+    Flash,
+    Redirect,
+};
 use rocket_contrib::json::Json;
 use rocket_contrib::templates::Template;
 
@@ -110,24 +117,30 @@ struct LoginData {
 }
 
 #[derive(Serialize)]
-struct EmptyContext {
+struct LoginFormContext {
+    message: Option<String>,
 }
 
 #[get("/login")]
-fn login_form() -> Template {
-    let context = EmptyContext {};
+fn login_form(flash: Option<FlashMessage<'_, '_>>) -> Template {
+    let context = LoginFormContext {
+        message: match flash {
+            Some(ref msg) => Some(msg.msg().to_string()),
+            _ => None,
+        },
+    };
     Template::render("login_form", &context)
 }
 
 #[post("/login", data = "<form_data>")]
-fn login(form_data: Form<LoginData>) -> String {
+fn login(form_data: Form<LoginData>) -> Result<Redirect, Flash<Redirect>> {
     let auth = BasicAuthentication {
         username: form_data.username.to_owned(),
         password: form_data.password.to_owned(),
     };
     match auth_user(&auth) {
-        Ok(ldap_user) => format!("OK! {:?}", ldap_user),
-        _ => format!("Bad :("),
+        Ok(_ldap_user) => Ok(Redirect::to("/")),
+        _ => Err(Flash::error(Redirect::to(uri!(login_form)), "Not able to authenticate with given credentials.")),
     }
 }
 

templates/login_form.html.tera

@@ -3,6 +3,9 @@
 {% block content %}
     <h1>Login</h1>
     <form action="/login" method="POST">
+        {% if message %}
+            <strong>{{ message }}</strong>
+        {% endif %}
         <fieldset>
             <legend>Login</legend>
             <div class="form-group">