How to send flash messages in Express 4.0?

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梦谈多话
梦谈多话 2020-11-28 03:26

So my web application requires authentication, and I have a signup page where if the person tries to sign up with an email that is already in the database, I want to show th

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  • 2020-11-28 03:49

    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.

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  • 2020-11-28 03:49

    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>
    <% } %>
    
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  • 2020-11-28 03:51

    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 %>
    
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  • 2020-11-28 03:58

    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

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  • 2020-11-28 04:03

    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.

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  • 2020-11-28 04:08

    In my case if i put the message display part in another EJS file and import it in my layout, i get the success and error both displayed initially without any text since the pager just loaded

    _message.ejs

    <% if(success_msg) { %>
        <div class="alert alert-success">
            <%= success_msg %>
        </div>
    <% } %>
    
    <% if(error_msg) { %>
        <div class="alert alert-danger">
            <%= error_msg %>
        </div>
    <% } %>
    
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