How to pass parameters to mysql query callback in nodejs

Question

I'm trying to figure out the correct way of passing custom data to a query call to be made available in the callback. I'm using MySQL library in nodejs (all latest versions).

I have a call to connection.query(sql, function(err, result) {...});

I couldn't find a way to 1) pass custom data/parameter to the call so that 2) it can be made available when the callback is invoked. So what is the proper way of doing so?

I have the following (pseudo-code):

... for (ix in SomeJSONArray) {     sql = "SELECT (1) FROM someTable WHERE someColumn = " + SomeJSONArray[ix].id;     connection.query(sql, function (err, result) {       ...       var y = SomeJSONArray[ix].id;     }; } 

From the code above, I need to be able to pass the current value of "ix" used in the query to the callback itself.

How do I do that?

Answer 1

If you are using node-mysql, do it like the docs say:

connection.query(     'SELECT * FROM table WHERE id=? LIMIT ?, 5',[ user_id, start ],      function (err, results) {      } ); 

The docs also have code for proper escaping of strings, but using the array in the query call automatically does the escaping for you.

https://github.com/felixge/node-mysql