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How to deal with async. FindOrCreate method for passport and mongoose

The 'Passport' authentication module requires the FindOrCreate method to log in. I use mongoose to save my users with the following scheme:

var UserSchema = new Schema({
    firstname: String,
    lastname: String,
    email: String,
    accounts: []
});

An array of accounts stores objects that represent facebook accounts, for example {provider: "facebook", uid: "someFacebookId"}.

My authentication strategy looks like this:

// Authentication Strategy
passport.use(new FacebookStrategy({
    clientID: CONFIG.fb.appId,
    clientSecret: CONFIG.fb.appSecret,
    callbackURL: CONFIG.fb.callbackURL
  },
  function(accessToken, refreshToken, profile, done) {
    // asynchronous verification, for effect...
    process.nextTick(function () {

      User.find({ 'accounts.uid': profile.id, 'accounts.provider': 'facebook' }, function(err, olduser) {

          if(olduser._id) {
            console.log('User: ' + olduser.firstname + ' ' + olduser.lastname + ' found and logged in!');
            done(null, olduser);
          } else {
            var newuser = new User();
            var account = {provider: "facebook", uid: profile.id};
            newuser.accounts.push(account);
            newuser.firstname = profile.name.givenName;
            newuser.lastname = profile.name.familyName;
            newuser.email = "TBD...";

            newuser.save(function(err) {
              if(err) { throw err; }
              console.log('New user: ' + newuser.firstname + ' ' + newuser.lastname + ' created and logged in!');
              done(null, newuser);
            });
          }
        });
    });
  }
));

Problem: After querying my database ( User.find(...)), the callback function is executed immediately without waiting for my database to respond. This results in an undefined object olduser. Therefore, I get a duplicate of the same user in my database every time that user tries to log in.

How to handle this asynchronous callback correctly?

+5
4

User.find , . User.findOne , if (olduser)..., , .

+4
process.nextTick(function () {
      var query = User.findOne({ 'fbId': profile.id });
      query.exec(function (err, oldUser) {
        console.log(oldUser);
        if(oldUser) {
          console.log('User: ' + oldUser.name + ' found and logged in!');
          done(null, oldUser);
        } else {
          var newUser = new User();
          newUser.fbId = profile.id;
          newUser.name = profile.displayName;
          newUser.email = profile.emails[0].value;

          newUser.save(function(err) {
            if(err) {throw err;}
            console.log('New user: ' + newUser.name + ' created and logged in!');
            done(null, newUser);
          }); 
        }
      });
    });
+1

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