Migrating node driver 1.4.x -> 2.2.x

[gwsy...@gmail.com]

Preface: Updating for mongodb 3.2 compatibility ... there are several fields that were previously set on actions that are no longer being set.

Have tried searching stackoverflow (which is where I discovered them originally) but have not located any info.

Specifically we look at the following (some no longer there) fields to see if a cached connection is still valid and can be reused:

[db].openCalled  :: used to be boolean once open() has been called, no longer there or moved

[db]._state   :: used to indicate the "state" (e.g. "connected"), no longer there or moved

[db].serverConfig.checkoutWriter()   ::  this would return an Error under certain failure conditions

Anyone have guidance on how to update the following code to achieve the same results?

exports.getMongoDBConnection = function(callback) {

   if (pooledConnection && pooledConnection.openCalled)

   {

     if (!!callback && typeof(callback) === "function") { callback(null, pooledConnection); }

   }

   else { // circa 2.2 always entering this since openCalled is gone

    logging.info("No available pooled connection, opening new mongo connection.");  

     MongoClient.connect(connectionString, mongoOptions, function (err, db) {

        if (err) {

           var error = "Error connecting to Mongo: " + err;

           logging.error(error, err);

           if (!!callback && typeof(callback) === "function") { callback(err); }

       } else {

           pooledConnection = db;  // cache the connection

            db.on('close', function() {

             if (db === pooledConnection) pooledConnection = null;

             if (this._callBackStore) {

              for(var key in this._callBackStore._notReplied) {

                 this._callHandler(key, null, 'Connection Closed!');   // notify any pending requests

               }

             }

           });

           db.on('reconnect', function() {

             logging.warn("mongoHelper.js", 'Mongo reconnect detected');

             if (this._callBackStore) {

               for(var key in this._callBackStore._notReplied) {

                 this._callHandler(key, null, 'Connection reconnected, waiting queries are no longer valid');

               }

             }

           });
...

exports.closeMongoDBConnection = function(db,force,callback) {

   if (db && db.openCalled) {

       var connection = db.serverConfig.checkoutWriter();

       if (!!connection && connection instanceof Error) {

         logging.warn("Closing failed mongo connection", connection);

         force = true;

       }

       if ((force || db !== pooledConnection)) {

         logging.info("Closing mongo connection in state: " + db._state);

         return db.close(true, callback);

       }

   }

   else if (!!callback && typeof(callback) === "function") callback(null,db);

};

re: http://stackoverflow.com/questions/10470123/using-db-open-with-mongodb-and-nodejs

     http://stackoverflow.com/questions/18688282/handling-timeouts-with-node-js-and-mongodb

[Christian Kvalheim]

Not sure what the intention of the code is. Maybe if you explain the use-case you have it might be easier to propose a solution. Relying on internal driver state however will not work and the only backward compatibility guarantees made, are for the public APIs.