Question

Ok I am making a blog system using MongoDB as the back end. I want to do the same thing as wordpress when you edit it saves the past versions and allows you to revert to them if needed.

I would like to do the same.

I have a few ways to doing it. but un sure if this is the best easiest way to do it and would like some suggestions.

the first is a find and the insert $SET

<?php
 $cursor = $collection->find(array("_id"=> new MongoId($data)));

        if ($cursor->count() > 0)
        {
              while( $cursor->hasNext() ) {
                foreach($cursor->getNext() as $key => $value)
                {
                    define("_".strtoupper($key), $value);
                }

              }

$cursor = $collection->update(array("_id" => new MongoId($data)),
 '$set'=>array("title"=>$data['TITLE'], "content"=>$data['content'], "past_versons"=>array("title" => _TITLE, "content" => _CONTENT)));
        }
?>

So my question is this the way I would do it.

here a sample JSON

{
"title":"blog title",
"content":"blog content",
"past_verson":[{"title":"blog title past","content":"past blog content"}]
}

Answer 1

In your example, you’re iterating over a MongoCursor even though you only expect to work with one document at most. MongoCollection::findOne() is going to be more appropriate here, as it will return the document array of the first result or null if no documents matched.

Even if you needed to iterate across multiple results, you’d do better to take advantage of the iterable nature of MongoCursor (it implements Iterator, which extends Traversable, which means you can use it in a foreach loop). I also don’t think define() is appropriate for storing what is essentially a temporary variable here. Moreover, suppose this code needed to run twice (error due to redefinition) or the title or content was not a scalar (another error).

Consider the following rewrite (I assumed $data['id'] is correct and you made a typo in the above code by using $data alone for the MongoId):

$document = $collection->findOne(array('_id' => new MongoId($data['id'])));

if (null !== $document) {
    $collection->update(
        array('_id' => new MongoId($data['id'])),
        array(
            '$set' => array(
                'title' => $data['title'],
                'content' => $data['content'],
            ),
            '$push' => array(
                'past_versions' => array(
                    'title' => $document['title'],
                    'content' => $document['content'],
                ),
            ),
        )
    );
}

One deviation here, which you may not need, is that I’m aggregating old versions into a past_versions array. We can use the $push operator to append to an array field in the document. Alternatively, you could simply use $set if you only need/want to store the most recent version.