How to properly initialize session data using passport.js having different strategies? - passport.js

Question

I'd like to setup some session data for the user if the user has logged in (authenticated) correctly, for instance, look up user in the database and determine his role, what parts of the app can be seen, etc.
But, I want to use different passport strategies for dev/localhost and for production.
Therefore, I plug in different strategies based on the different ENV settings.
What troubles me is where do I put the common code, for both(any) strategies, the one that is executed (only once!) after a user authenticated correctly.
I don't wont to embed it in the strategies and duplicate the code.
Edited:
Example:
Say I have this code in my local strategy:
passport.use(new LocalStrategy(
function(username, password, done) {
User.findOne({ username: username }, function (err, user) {
if (err) { return done(err); }
if (!user) { return done(null, false); }
if (!user.verifyPassword(password)) {
<setup session data code here>
return done(null, false);
}
return done(null, user);
});
}
));
Now, in my other strategy I'd have to repeat <setup session data code here>.
I want to move that part of the code outside of both my strategies, so that strategies would only authenticate users.
I'm looking for some onSuccessfulAuthorization handler/event in the passport to execute that code once the authorization succeeds, regardless of the current strategy used.

Answer 1

There are more than one way to do this. Depending on your situation, you can come up with something that works best for you.
I'd suggest having another file session_setup.js or even common.js if you need more functions. Put your common codes in there as functions, then require them whenever you need it.
session_setup.js:
module.exports.setupSession = function (user) {
// put your common code here
}
And in your strategy file:
let setupSession = require('./session_setup.js');
passport.use(new LocalStrategy(
function(username, password, done) {
User.findOne({ username: username }, function (err, user) {
if (err) { return done(err); }
if (!user) { return done(null, false); }
if (!user.verifyPassword(password)) {
setupSession(user); // you can pass whatever argument you need there.
return done(null, false);
}
return done(null, user);
});
}
));
If the login in setupSession is asynchronous, you can accept a callback argument as well, or better, return a Promise and in the strategy:
if (!user.verifyPassword(password)) {
setupSession(user).then(() => {
done(null, false);
});
}
It all depends on what you actually do in that piece of code. You get the idea.