Nodejs async.waterfall callbacks argument mismatch?

Question

I am trying to use async.waterfall to execute queries against a database sequentially so that I can rollback all of them if there is an error on one. Below is my code:

 function _getDBConnection(callback) { try { dbService.getConnection(function(connection) { callback(null, connection); }); } catch (e) { callback(e, null); } } function _insertNewUser(newUser, connection, callback) { if (connection) { var query = 'somequery'; // Start a transaction connection.beginTransaction(function(error) { if (error) { callback(error, connection, null); } // Fire the query connection.query(query, function(error, result) { if (error) { callback(error, connection, null) } else { callback(connection, newUser, result.insertId); } }); }); } else { callback('Error: no connection in ', null, null); } }; module.exports.doRegister = function(req, res) { // Collect all the params coming from the UI. var newUser = {'object with UI params'}; console.log("Trying to register the user..."); async.series([ _getDBConnection, async.apply(_insertNewUser, newUser) ], function(err, success) { if (err) { console.log(err); } else { res.status(200).json({ success: true, message: 'User registeration successfully.' }); } }); }; 

Problem: I am not receiving the connection object from _getDBConnection function into the second function (_insertNewUser) properly. It's coming as undefined, and as a result, I am getting the following error.

TypeError: connection.beginTransaction is not a function ~~~~ stack trace ~~~~ Error: Callback was already called ~~~~ stack trace ~~~~

I think I am getting the 'callback' function instead of the connection object in the _insertNewUser function, which is not expected. What am I doing wrong?

In case it matters, I have other functions/queries after the _insertNewUser that are getting called but, I have removed them from the code for brevity.

Answer 1

As i can see you are using async.series. Probably you should use async.waterfall to pass result of one function to another.

Nodejs async series - pass arguments to next callback