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How to send flash messages in Express 4.0?

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How do I use Express flash message?

To implement flash messages in NodeJs with connect-flash module, you need to install the required dependencies using the command. Express: Required by the library connect-flash to run. Express-session: to create a session whenever a message is flashed, so that the user can be redirected to a particular page.

Can we send flash message?

Flash SMS on Android devices Not all Android devices display Flash SMS in the same way. However, it is likely that Android devices do not display Flash SMS in the lock screen. Instead, the message might show as a Flash SMS after unlocking the device or as a regular SMS.

What are flash messages?

With Flash calls, WhatsApp is adding another option with which users can choose to receive an automated call for verifying their phone number. This means that Flash calls allow WhatsApp to call their device and verify automatically, eliminating the need for any other text message-based verification.

What is connect-flash in node JS?

Connect-flash module for Node. js allows the developers to send a message whenever a user is redirecting to a specified web-page. For example, whenever, a user successfully logged in to his/her account, a message is flashed(displayed) indicating his/her success in the authentication.


This Gist should answer your question:

https://gist.github.com/raddeus/11061808

in your application setup file:

app.use(flash());

Put that right after you set up your session and cookie parser. That's really all you should need to use flash.

You are using:

req.flash('signupMessage', anyValue);

before redirecting to /signup right?

Here's a fun little tidbit that I currently use for a personal site(in my main application file):

app.use(function(req, res, next){
    res.locals.success_messages = req.flash('success_messages');
    res.locals.error_messages = req.flash('error_messages');
    next();
});

Now every view will have access to any error or success messages that you flash. Works well for me.

One final thing (this is nitpicky but you may gain some knowledge). If you change:

<% if (message.length > 0) { %>

to:

<% if (message) { %>

It will work the same way but will not fail if message is undefined. undefined and empty strings are both considered "falsy" values in javascript.

EDIT: My cookie/session/flash setup goes as follows:

app.use(cookieParser('secretString'));
app.use(session({cookie: { maxAge: 60000 }}));
app.use(flash());

Maybe seeing your application setup code would help. Also note that using app.configure is no longer necessary in Express 4.

Final edit: https://gist.github.com/raddeus/11061808

That is a working example. Go to localhost:3000 after running that app and you should see ['it worked'] on your screen.


https://gist.github.com/brianmacarthur/a4e3e0093d368aa8e423

I, too, was initially confused by flash messages in Express 4. The confusion for me arose partly from the distinction between the concept of flash messaging, a temporary message available to a template, and the various implementations of flash messaging, which include express-flash, other modules, and custom middleware.

Just to expand on the excellent response from Thad Blankenship above, I created a Gist for the beginner that includes two approaches to flash messages--the express-flash module and custom middleware--rendered in jade, ejs, or handlebars.

The readme includes details about the getter--req.flash(type)--and setter--req.flash(type, message)--methods exposed by express-flash and how they differ from the exploitation of the res.locals and req.session objects exposed by express-session in the custom middleware.


To show flash message you have to install flash module in your project using cmd.

npm install express-session --save

npm install cookie-parser --save

npm install connect-flash --save

Now you have to add some code to the app.js file to access those modules. Let’s add these code.

var session = require('express-session');

var cookieParser = require('cookie-parser');

var flash = require('connect-flash');

var app = express();

app.use(cookieParser('secret'));

app.use(session({cookie: { maxAge: 60000 }}));

app.use(flash());

Now generate flash message

req.flash('success', 'Registration successfully');
res.locals.message = req.flash();

To show the flash message in view file use the code

<% if(locals.message){ %>
    <div class="alert alert-success" role="alert">
        <strong>Well done!</strong> <%=message.success%>
    </div>
<% } %>

After researching for two days and wanting to give up A LOT I've finally found out how to use connect-flash (u do not need cookie-parser) a few main things use (return res.redirect) instead of res.render it does not like render for callbacks I don't know why. Take a look at my code to get a visual.

app.js

var express                 = require("express"),
    bodyParser              = require("body-parser"),
    mongoose                = require("mongoose"),
    passport                = require("passport"),
    LocalStratagy           = require("passport-local"),
    User                    = require("./user"),
    passportLocalMongoose   = require("passport-local-mongoose"),
    flash                   = require('connect-flash'),
    app                     = express();
    //using express-session
app.use(require("express-session")({
    secret:"The milk would do that",
    resave: false,
    saveUninitialized: false
}));
app.use(flash());

app.use(function(req, res, next){
    res.locals.message = req.flash();
    next();
});


//connectiong to a specific database
    mongoose.connect("mongodb://localhost/LoginApp");


    //so body-parser works
app.use(bodyParser.urlencoded({extended: true}));

//making it so express uses the public dir
app.use(express.static("public"));

//setting the view engine to ejs
app.set("view engine", "ejs");


// so passport works
app.use(passport.initialize());
app.use(passport.session());

//authenticated data from the login form
passport.use(new LocalStratagy(User.authenticate()));

//reading the data and encoding it
passport.serializeUser(User.serializeUser());

//reading the data and unencoding it
passport.deserializeUser(User.deserializeUser());


//ROUTES
app.get("/", function(req, res){
    res.render("index");
});


// AUTH ROUTES

//show login
app.get("/login", function(req, res){
    req.flash("error", "")
    res.render("Login");
});

//handle login form data
app.post("/login", passport.authenticate("local",{
    failureRedirect: "/login",
    failureFlash: true,
}) ,function(req, res){
    req.flash("success", "Logged in");
    return res.redirect("/");
});

//Show signup form
app.get("/signup", function(req, res){
    res.render("Signup");
});

//handle signup form data
app.post("/signup", function(req, res){
    User.register(new User({username: req.body.username}), req.body.password, function(err, user){
        if(err){
            req.flash("error", err.message);
            return res.redirect("/signup");
        }
        passport.authenticate("local")(req, res, function(){
            req.flash("success", "successfuly Signed up");
            return res.redirect("/");
        });
    });
});



app.listen(3000, function(){
    console.log("server started");
});

Header.ejs

  <!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
        <meta name="description" content="Fully responsive project with a backend">
        <link rel="stylesheet" href="main.css">
        <script src="https://code.jquery.com/jquery-3.4.0.min.js"></script>
        <!-- animated css -->
        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.7.0/animate.css">

        <!-- Bootstrap CSS -->
        <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
        <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.8.1/css/all.css" integrity="sha384-50oBUHEmvpQ+1lW4y57PTFmhCaXp0ML5d60M1M7uH2+nqUivzIebhndOJK28anvf" crossorigin="anonymous">
        <title>wire frame chal</title>
    </head>
    <body>

        <h1><%= message.error %></h1>
        <h1><%= message.success %></h1>

Login.ejs

   <% include ../partials/header %>
<form method="POST" action="/login">
    <input type="text" name="username" placeholder="username">
    <input type="password" name="password" placeholder="password">
    <button>Submit</button>
</form>


<% include ../partials/footer %>

Signup.ejs

  <% include ../partials/header %>

<form method="POST" action="/signup">
    <input type="text" name="username" placeholder="username">
    <input type="password" name="password" placeholder="password">
    <button>Submit</button>
</form>


<% include ../partials/footer %>

This might be an old post guys but I just became aware of express-flash-2. It appears to be less buggy with Express 4 seems to have solved all my problems.

npm link