Mongoose User model for handling local and social auth providers

So I found a working solution for myself which might help other people with the same problem. In my User model I have my usual fields and for each social provider I have a separate array like so (users/User.js):

let userSchema = mongoose.Schema({    email: { type: String, unique: true },    name: { type: String },    password: { type: String },    roles: [String],    confirmation_code: String,    confirmed: { type: Boolean, default: false },    facebook: {        id: String,        token: String,        email: String,        name: String    },    google: {        id: String,        token: String,        email: String,        name: String    }}, { timestamps: true });

When authenticating with a social provider I make an extra check if a user with the same email already exists. If it doesn't, I create a new user. If it does I just add the social provider data (id, token, etc.) to the already existing users array like so (config/passport.js):

passport.use(new FacebookStrategy({    clientID: oauth.facebook.clientID,    clientSecret: oauth.facebook.clientSecret,    callbackURL: oauth.facebook.callbackURL,    profileFields: ['id', 'emails', 'name']},    function (accessToken, refreshToken, profile, done) {        process.nextTick(function () {            User.findOne({                $or: [                    { 'facebook.id': profile.id },                    { 'email': profile.emails[0].value }                ]            }, function (err, user) {                if (err) {                    return done(err);                }                if (user) {                    if (user.facebook.id == undefined) {                        user.facebook.id = profile.id;                        user.facebook.token = accessToken;                        user.facebook.email = profile.emails[0].value;                        user.facebook.name = profile.name.givenName + ' ' + profile.name.familyName;                        user.save();                    }                    return done(null, user);                } else {                    let newUser = new User();                    newUser.facebook.id = profile.id;                    newUser.facebook.token = accessToken;                    newUser.facebook.email = profile.emails[0].value;                    newUser.facebook.name = profile.name.givenName + ' ' + profile.name.familyName;                    newUser.name = profile.name.givenName + ' ' + profile.name.familyName;                    newUser.email = profile.emails[0].value;                    newUser.save(err => {                        if (err) {                            console.log(err);                            throw err;                        }                        return done(null, newUser);                    });                }            });        });    }));

With this approach you can connect one profile with multiple social providers. However there is one downside. If the user registers a new profile for the first time through a social provider, he won't have a password because social providers don't give back password data (duh). He just needs to change (set) his password through his profile afterwards.