Node.js crashes on MySQL query

Question

I need help with this problem I got. I have login script that crashes node if the username or password isn't in the database, here the code:

/* Login */
exports.login = function(req, res){
    var post = req.body;
    var mysql = require('mysql');
    var db = mysql.createConnection({
      host      : 'localhost',
      user      : 'root',
      password  : 'root',
      database  : 'node01',
    });
    var selectStmt = 'SELECT * FROM users WHERE name = "' + post.user +'"';
    db.connect();

    db.query(selectStmt, function(err, rows, fields) {
      if(err) throw err;
      else if(rows[0].name == post.user && rows[0].password == post.password){
        req.session.auth_id = rows[0].id;
        req.session.user = rows[0].name;
        res.redirect('/adminindex');
      }
      else res.redirect('/admin');
    });

    db.end();
};

and the error I get

TypeError: Cannot read property 'name' of undefined
at Query.exports.login [as _callback] (../node-project01/routes/login.js:18:19)
at Query.Sequence.end (../node-project01/node_modules/mysql/lib/protocol/sequences/Sequence.js:66:24)
at Query._handleFinalResultPacket (../node-project01/node_modules/mysql/lib/protocol/sequences/Query.js:138:8)
at Query.EofPacket (../node-project01/node_modules/mysql/lib/protocol/sequences/Query.js:122:8)
at Protocol._parsePacket (../node-project01/node_modules/mysql/lib/protocol/Protocol.js:165:24)
at Parser.write (../node-project01/node_modules/mysql/lib/protocol/Parser.js:60:12)
at Protocol.write (../node-project01/node_modules/mysql/lib/protocol/Protocol.js:32:16)
at Socket.ondata (stream.js:38:26)
at Socket.EventEmitter.emit (events.js:96:17)
at TCP.onread (net.js:396:14)

Any ideas on how to fix this?

Don't put code and error on a separate site - put them in your question! — marc_s

Vih Damarques Vih Damarques · Accepted Answer · 2013-03-03T20:17:57

Well, considering that your question is from December, I imagine that you have already solved the problem. However, your problem is probably because your query have no results, then 'rows[0]' is undefined. before using the 'rows' variable you always should test if there is any result, like:

if (rows.length > 0) {
  // your code here
}

regards,

Node.js crashes on MySQL query

1 Answers