node.js cassandra connecion

Question

This is nodejs program. How do I return the result?

executeCQLQuery = function(query, PooledConnection, options) {
  var hosts = [options.host + ":" + options.port];
  var connection_pool = new PooledConnection({
    'hosts': hosts,
    'keyspace': options.keyspace
  });

  connection_pool.execute(query, [], function (err, rows) {
    if (err) {
      console.log(err);
    } else {
      return rows;
    }
    //console.log(rows);
    result = rows;
  });
  console.log(result);
  return result;
}
exports.executeCQLQuery = executeCQLQuery;

Answer 1

Instead of having an inline callback in the execute function (where you check your rows error) you could pass the callback in as Tamil suggested, like this

connection_pool.execute(query, [], callback);

Then you could pass the callback into your exported function

executeCQLQuery = function(query, PooledConnection, options, callback) {
  ...
}

Answer 2

Keep in mind that the cassandra node library is asynchronous, like most things in node.js. You need to do things the node way, with a callback function:

executeCQLQuery = function(query, PooledConnection, options, callback) {
var hosts = [options.host + ":" + options.port];
var connection_pool = new PooledConnection({
  'hosts': hosts,
  'keyspace': options.keyspace
});

connection_pool.execute(query, [], callback);

exports.executeCQLQuery = executeCQLQuery;

then use it like this:

executeCQLQuery('select foo from bar where key="bam"', PooledConnection, {host:'foo', port:1234}, function(err, rows) {
  // check for err
  // do something useful with rows.
});

Another suggestion: It doesn't make sense to use PooledConnection as an arg. You should instantiate it before calling executeCQLQuery.

The test cases in cassandra-node are always a good place to start: http://code.google.com/a/apache-extras.org/p/cassandra-node/source/browse/test/test_driver.js#280