How to save a modified object in mongodb using Node.JS Driver

Question

I want to find, modify and afterwards save an object in MongoDB. It looks like that:

var message = req.body;
db.collection('user', function(err, collection) {
  collection.findOne({'facebook_id':req.params.facebook_id}, function(err, item) {
    if(item) {
      item.messages.push({'value': message.value, 'date': message.date});
      //save Object
    }
  });
});

How can I now save the changes I made to the database?

Or should I instead use .update()? The problem here is, that I don't want to swap the whole object, but much more insert something into an array of that object.

Thanks & Best, Marc

Answer 1

collection.update({'facebook_id':req.params.facebook_id}, 
  {$push: { messages: {'value': message.value, 'date': message.date} } }, function(err) {

});

Use the $push operator to add a value to an array directly in the database. http://docs.mongodb.org/manual/reference/operator/update/push/

Note that this is much more efficient than updating the entire object, especially for large objects.