I'm using NodeJS, PassportJS, MySQL, and Sequalize(ORM for MySQL). This code is from my Passport.JS file. When a user registers on my website if the username or email is taken I will return an error. If both username, email can't be found in database a new create account will be created.

The error I'm getting when I register on my website is...

Unhandled rejection TypeError: Cannot read property 'username' of null
    at null.<anonymous> (/home/ubuntu/workspace/Authentication.1/config/passport/passport.js:50:16)
    at tryCatcher (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:512:31)
    at Promise._settlePromise (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:569:18)
    at Promise._settlePromise0 (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:614:10)
    at Promise._settlePromises (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:693:18)
    at Async._drainQueue (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:133:16)
    at Async._drainQueues (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:143:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:17:14)

My code is:

        User.findOne({
            // SELECT * FROM users WHERE username = username || email = ... 
            where: {
                $or: [{username: username}, {email: req.body.email}]
            }
        }).then(function(user){

        // GETTING ERROR HERE. If username is already in database
        if(user.username !== null && user.username == req.body.username) {
          return done(null, false, console.log("USER TAKEN"),{message : 'That username is already taken'} );
        }

        // If email is already in database return err.
        else if(user.email !== null && user.email == req.body.email) {
          return done(null, false, console.log("EMAIL TAKEN"),{message : 'That email is already taken'} );
        }

        else [code for create new account]...

I'm using NodeJS, PassportJS, MySQL, and Sequalize(ORM for MySQL). This code is from my Passport.JS file. When a user registers on my website if the username or email is taken I will return an error. If both username, email can't be found in database a new create account will be created.

The error I'm getting when I register on my website is...

Unhandled rejection TypeError: Cannot read property 'username' of null
    at null.<anonymous> (/home/ubuntu/workspace/Authentication.1/config/passport/passport.js:50:16)
    at tryCatcher (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:512:31)
    at Promise._settlePromise (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:569:18)
    at Promise._settlePromise0 (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:614:10)
    at Promise._settlePromises (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:693:18)
    at Async._drainQueue (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:133:16)
    at Async._drainQueues (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:143:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:17:14)

My code is:

        User.findOne({
            // SELECT * FROM users WHERE username = username || email = ... 
            where: {
                $or: [{username: username}, {email: req.body.email}]
            }
        }).then(function(user){

        // GETTING ERROR HERE. If username is already in database
        if(user.username !== null && user.username == req.body.username) {
          return done(null, false, console.log("USER TAKEN"),{message : 'That username is already taken'} );
        }

        // If email is already in database return err.
        else if(user.email !== null && user.email == req.body.email) {
          return done(null, false, console.log("EMAIL TAKEN"),{message : 'That email is already taken'} );
        }

        else [code for create new account]...

• javascript
• mysql
• node.js
• sequelize.js

• 1 user is null, not the username. – Andrew Li Commented Aug 8, 2017 at 4:33
• 2 Please don't make more work for others by vandalizing your posts. By posting on the Stack Exchange (SE) network, you've granted a non-revocable right, under a CC BY-SA license, for SE to distribute the content (i.e. regardless of your future choices). By SE policy, the non-vandalized version is distributed. Thus, any vandalism will be reverted. Please see: How does deleting work? …. If permitted to delete, there's a "delete" button below the post, on the left, but it's only in browsers, not the mobile app. – Makyen ♦ Commented Dec 18, 2019 at 15:49

1 Answer 1

Your issue is from the first check in your if statement. In the event the user isn't found, user will be null and the statement user.username !== null will result in the error message you are getting.

You should perform a null check on the object as a whole, not the property. if(user!== null && user.username == req.body.username){...}