Catch MySQL error when record does not exist in NodeJS

Issue

I am trying to figure out how I can catch an error when a requested id is not found in the Database records.

My code is:

router.get('/users/:id', function(req, res) {

    getId = req.params.id

    db.con.query('SELECT * FROM employees where id=?', getId, function(err, results) {

       if (err) {
            console.log('error in query')
            return

        } else {
            obj = {
                id: results[0].id,
                name: results[0].name,
                location: results[0].location
                // error should be cached here when a requested results[0].id is not found
            }
            res.render('showuser');
        }
    })

});

In the console, I get the following error when a non-existed id is requested as it should be, however I cannot catch this error programmatically.

throw err; // Rethrow non-MySQL errors
^
ReferenceError: id is not defined
at Query._callback (C:\NodeJS\CRUD\CRUD-4\routes\add.js:21:13)

Node: v8.8.0

Express: v4.15.5

Solution

Try this:

try{
  obj = {
     id: results[0].id,
     name: results[0].name,
     location: results[0].location
  }
}catch(err){
  //handle error
}

try {...}catch... is how you handle exceptions in JavaScript. You can read more about it here.

Answered By – Chris Thompson

This Answer collected from stackoverflow, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0

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