Using Node, Q, and mongodb save an array of objects to a mongo collection.

promise-upsert

var saveObjects = function (objects) {
    var MongoC = MongoClient;
    var mongoConnect = Q.nbind(MongoC.connect, MongoC);

    return mongoConnect(dbString).then(function (db) {
      var DocumentCollection = db.collection('collection');
      var documentCollectionUpsert = Q.nbind(DocumentCollection.update, DocumentCollection);
      //Use upsert option. 
      var options = { 'upsert' : true };
      var upsertPromises = objects.map(function (obj) {
          return documentCollectionUpsert(obj, obj, options);
      });

      return Q.all(upsertPromises).finally(function () {
        db.close();
      });

    });
  };