NodeJS Express App - Showing flash messages via Handlebars - node.js

Question

I'm hoping someone can help with showing flash messages in Express via a Handlebars view (which uses the bootstrap markup).
In app.js I have the below modules and middleware to try and get flashes working
//require modules
const express = require('express');
const cookieParser = require('cookie-parser');
const bodyParser = require('body-parser');
const expressValidator = require('express-validator');
const hbs = require('express-handlebars');
const session = require('express-session');
const flash = require('connect-flash');
const routes = require('./routes/index');
const app = express();
// view engine setup
app.engine('hbs', hbs({extname: 'hbs', defaultLayout: 'layout',layoutsDir: __dirname + '/views/layouts/'}));
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'hbs');
app.use(express.static(path.join(__dirname, 'public')));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(expressValidator());
app.use(cookieParser());
app.use(session({
secret: process.env.SECRET,
key: process.env.KEY,
resave: false,
saveUninitialized: false,
store: new MongoStore({ mongooseConnection: mongoose.connection })
}));
app.use(flash());
app.use((req, res, next) => {
res.locals.h = helpers;
res.locals.flashes = req.flash();
res.locals.user = req.user || null;
res.locals.currentPath = req.path;
next();
});
app.use('/', routes);
module.exports = app;
and a route
router.post('/store/add', storeController.createStore);
which has the controller function
exports.createStore = async (req, res) => {
const store = new Store(req.body);
await store.save();
req.flash('error', 'leave a review');
console.log('my-messages',req.flash());
res.redirect('/');
};
when I create a new store and am redirected to homepage the console.log shows the correct value my-messages { error: [ 'leave a review' ] } but I cannot get it into the view
my homepage ('/') view is
<h1>{{title}}</h1>
<p>Hi! Welcome to {{title}} </p>
<p>This page was built by {{created}}</p>
{{#if message}}
<div class="alert alert-danger">{{message}}</div>
{{/if}}
{{#if errors}}
{{#each errors}}
<div class="error">
{{msg}}
</div>
{{/each}}
{{/if}}
but nothing shows up. I've read quite a few similar questions on SO, but can't seem to get this right.
Any help much appreciated.

Answer 1

OK, so this is how I've worked things based on https://gist.github.com/brianmacarthur/a4e3e0093d368aa8e423 from this https://stackoverflow.com/a/28221732/1699434 answer.
After app.use(flash()) in app.js I added:
app.use(function(req, res, next){
// if there's a flash message in the session request, make it available
in the response, then delete it
res.locals.sessionFlash = req.session.sessionFlash;
delete req.session.sessionFlash;
next();
});
In my routes file (index.js) I added the example in the gist:
router.all('/session-flash', function( req, res ) {
req.session.sessionFlash = {
type: 'info',
message: 'This is a flash message using custom middleware and express-session.'
}
res.redirect(301, '/');
});
Then I created a handlebars partial message.hbs (which makes use fo the contains helper from npmjs.com/package/handlebars-helpers:
{{#if sessionFlash.message}}
<div id="flash-messages" class="container">
{{#contains sessionFlash.type "info"}}
<div class="alert alert-info">
{{{sessionFlash.message}}}
</div>
{{/contains}}
{{#contains sessionFlash.type "success"}}
<div class="alert alert-success">
{{{sessionFlash.message}}}
</div>
{{/contains}}
{{#contains sessionFlash.type "warning"}}
<div class="alert alert-warning">
{{{sessionFlash.message}}}
</div>
{{/contains}}
{{#contains sessionFlash.type "error"}}
<div class="alert alert-danger">
{{{sessionFlash.message}}}
</div>
{{/contains}}
</div>
{{/if}}
I can then include this in my other handlebars templates {{> message}}. This gives me flash messages carrying bootstrap styling.
Unfortunately I'm not able to send multiple flashes at the same time (either of the same or different types) but I think this is discussed in https://gist.github.com/brianmacarthur/a4e3e0093d368aa8e423 anyway as a limitation of the middleware approach. As I learn more maybe I'll address this but I don't have a use case for multiple flash messages at the moment anyway :)