How do I use req.flash() with nunjucks? - node.js

Question

I am using connect-flash to pass the flash message. In my controller, I am using the following code if (!req.user) {
req.flash("error_msg", "User not found !!");
return res.redirect(307, '/');
}
In my view, I tried
{{ error_message }}
{{ req.flash('error_message') }}
{{ req.flash.get('error_message') }}
But none of it works. What's the current syntax to parse the flash message in nunjucks ?

Answer 1

First of all you have to install "express-flash" and put below code in app.js
app.js
const flash = require('express-flash');
In Your Controller put below code when you want to pass message
req.flash('error_msg', "User not found !!");
return res.redirect(307, '/');
Put below code in your view file where you want to display message
<% if (typeof messages.error_msg !='undefined') { %>
<p class="error"><%= messages.error_msg %></p>
<% } %>

Answer 2

For anyone facing the same problem you can access the variable using {{ req.session.flash.error_msg }}

Answer 3

If you are using express js and nunjucks as template this is what I have done
in app.js
const flash = require('express-flash');
app.use(flash());
in Routes/controller code
try {
await User.deleteOne({_id:req.params._id}).exec()
req.flash("success_msg", "User deleted");
return res.redirect('/admin/users')
}
in Layout or view file
{% if messages.success_msg %}
<div class="alert alert-success" role="alert">
{{ messages.success_msg }}
</div>
{% endif %}

Answer 4

With connect-flash package, you cannot directly use req.flash in template engine. You need to add a middleware that adds the flash message to the res.locals which can be accessed in template rendering.
Here is a short code snippet.
// this part should be before all the request resolver.
// adding flash function to response locals
app.use((req,res,next)=>{
res.locals.flash = (arg) => { return req.flash(arg) };
next();
});
// request resolver
app.get("/",(req,res)=>{
req.flash("info","show me");
res.render("index.njk",{});
});
app.listen(8080,()=>{...})
In nunjucks file:
<h3>{{ flash("info") }}</h3>