how to get value from sql in express?

Question

I am stuck @ one of the problem in express node js. I am getting error "url not defined"

 app.get("/id", function(req, res) {
 var id = req.param("id");
  connection.query('SELECT `url` FROM dynamic_url where id ='+req.param("id"), function          (error, rows, fields) {
 //how do i get the values of url here
res.send("value of url is " + url);
});
});

I can't test it right now but I would say you should use: rows[0].url (if it won't work just do console.log(rows) and you will see response structure). — tomekK, Nov 20 '13 at 12:08

Paul Mougel · Answer 1 · 2013-11-20T12:13:42.507

1

You're getting this error because the url variable isn't defined anywhere.

The results of the MySQL request are available in the second parameter of the callback:

app.get("/id", function(req, res, next) {
  var id = req.param("id");
  connection.query('SELECT `url` FROM dynamic_url where id ='+req.param("id"), function (error, rows, fields) {
    if (err) {
      return next(err);
    }
    var url;
    if (rows.length === 0) {
      url = 'URL not available in database'
    } else {
      url =  rows[0].url;
    }
    res.send("value of url is " + url);
  });
});

Check mysql's documentation for a sample request.

edited Nov 20 '13 at 12:13

answered Nov 20 '13 at 12:08

Paul Mougel

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Indeed, forgot the last parameter. Updated my answer to include it. – Paul Mougel Nov 20 '13 at 12:14
This is not an error. The `rows` array contains objects. Please use `JSON.stringify()` or `console.log()` in order to know what they contain. – Paul Mougel Nov 20 '13 at 13:14
Okay, is there any method to get string data or any conversion which convert json to string – user2834795 Nov 20 '13 at 13:24
As stated in my previous comment, `JSON.stringify(rows)` will transform an object into a string. – Paul Mougel Nov 20 '13 at 16:20

how to get value from sql in express?

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