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JavaScript User Authentication With Express and Mongo Sessions and Cookies Creating the Profile Route and Page

Lucas Santos
Lucas Santos
19,315 Points
Posted by Lucas Santos
Lucas Santos
19,315 Points

Can you please explain your use of the .exec method

Dave McFarland

I understand what the .exec method is and that it's a method on the RegularExpression Object but the way you use this function does not make sense or was not explained very well. From my understanding the method is suppose to match a string with the expression but instead your giving it an anonymous function??

You used it twice:

  1. in the User Schema:
UserSchema.statics.authenticate = function(email, password, callback) {
  User.findOne({ email: email })
      .exec(function (error, user) {
        if (error) {
          return callback(error);
        } else if ( !user ) {
          var err = new Error('User not found.');
          err.status = 401;
          return callback(err);
        }
        bcrypt.compare(password, user.password , function(error, result) {
          if (result === true) {
            return callback(null, user);
          } else {
            return callback();
          }
        })
      });
}

and 2. on the route for /profile

User.findById(req.session.userId)
  .exec(function (error, user) {
    if (error) {
      return next(error);
    } else {
      return res.render('profile', { title: 'Profile', name: user.name, favorite: user.favoriteBook });
    }
  });

.exec method docs

thank you.

2 Answers

akak
akak
29,445 Points
akak
akak
29,445 Points

Hi, You are correct there is an .exec method on a Regex object. But since it's not on reserved methods name list: http://www.w3schools.com/js/js_reserved.asp anyone can create:

var myObject = {
  exec: function () {
      return 'Hello world';
  }  
}

and you would do myObject.exec() to get hello world;

You can read more about mongoose exec here: http://mongoosejs.com/docs/queries.html.

In short: exec just executes your query and runs callback function with the data from the query.

Lucas Santos
Lucas Santos
19,315 Points
Lucas Santos
Lucas Santos
19,315 Points

Ahh I see so that's where the confusions lies. Thanks for the head up akak!

Marcus Thelin
Marcus Thelin
1,188 Points
Marcus Thelin
Marcus Thelin
1,188 Points

So as I see it, the .exec function is used to easily handle error and the result from mongoose. If you're only interesting in getting the user into some variable, you can do it in an async-await function e.g

async function(){
   let user = await User.findOne({INFO TO SEARCH}); //Stores the user in the user variable
}

But in this case the exec function is the best usage! :D Happy coding!