CODEWITHSUNDEEP
node.jsmongodb
Zobla
Zobla

Reputation: 123

What gets returned from mongoDB query if user is not found?

I am building login system and want to check whether user exists in database and if passwords match. Later one works good but cant figure out first if statement. 

        try{
               const foundUser = await User.find({"username": req.body.username});
               if(foundUser === [])   // returns false
               res.send('user not found')
               else if(foundUser[0].password === req.body.password)
               res.send('success')
               else
               res.send('invalid password')
           }catch(err){
               res.send('Something went wrong', err)
           }

When tested using postman i commented out everything below first line (not catch block) and just sent foundUser variable as response. The value i got is []. Now my if statement compares [] === [], returns false and triggers catch block. Why this happens?

Upvotes: 1

Views: 724

Answers (1)

Muhammad Ali
Muhammad Ali

Reputation: 2014

find will return array and findOne will return object you can easily check with the length of an array 

 if (foundUser.length === 0)

and it is going to catch block because your first statement is false and second statement is 

 if (foundUser[0].password.....

foundUser is empty and you are getting first index object and comparing password

Upvotes: 1

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