MapReduce with PHP and MongoDB

Question

I'm fairly new to Mongo and I have what I thought was a simple question. How do I do MapReduce with PHP and the non legacy MongoDB driver http://php.net/manual/en/set.mongodb.php or the higher level package mongodb/mongodb found at https://packagist.org/packages/mongodb/mongodb?

Every example I've seen seems to use the legacy driver (http://php.net/manual/en/book.mongo.php). They all use the MongoCode object, which doesn't exist in mongodb.php. It exists in mongo.php (the legacy driver). When I try and use it, it will say that "Class 'MongoCode' not found".

My code looks something like:

$function = "function() { emit(this); }";
$map = new \MongoCode($function);

$command = $db->command([
    "mapreduce" => "db.archiveData",
    "map" => $map,
    "query" => $query,
    "out" => "data"
]);

To make things more confusing, when I look at the source at https://github.com/mongodb/mongo-php-library, there is a unit test for MapReduce (https://github.com/mongodb/mongo-php-library/blob/4dc36f6231df133a57ff0dc5a0123945133d25ba/tests/Operation/MapReduceFunctionalTest.php). But it uses the MongoDB\Operation\MapReduce, which doesn't seem to exist in the 1.1 version of mongodb/mongodb.
I thought maybe I would call it on the server using JavaScript. But when I look at http://php.net/manual/en/mongodb.execute.php, it says it "is deprecated in MongoDB 3.0+". So that doesn't feel like something I should use.

So is it that:

MapReduce is not supported with mongodb/mongodb. Or maybe it is not supported yet, but will be?
I have to use the legacy driver for MapReduce?
I have to figure out a way to call db.collection.mapReduce via JavaScript on the server?
I have to use the Aggregation Pipeline (https://docs.mongodb.com/manual/aggregation/) to do map reduce type of actions? But that feels much more limited.

What am I missing?

Have a check on this (if you haven't already): github.com/mongodb/mongo-php-library/issues/379 (Jun 19 2017), it says something about MongoDB\Database::command() and that MapReduce is not yet implemented. — Parziphal
– Parziphal, Commented Sep 28, 2017 at 18:36
Thanks @Parziphal. Good find. Not what I was hoping for, but it doesn't sound like the new library supports it. I also just discovered that I cannot use the legacy driver because it doesn't look like it's supported on PHP 7.0 (docs.mongodb.com/ecosystem/drivers/php/#compatibility) which we are using. — Randar Puust
– Randar Puust, Commented Sep 29, 2017 at 17:03
Yeah, I had a very similar problem long time ago, PHP 7.0, new mongo drivers that are incomplete... how we fixed it?... I don't remember, but around that time we started using Facebook's Parse so we stopped touching MongoDB directly and I started to use Node more often. So actually I never found a solution. — Parziphal
– Parziphal, Commented Sep 29, 2017 at 19:38

Randar Puust · Accepted Answer · 2017-10-06 21:02:38Z

So I now have clarity on where things are at.

MapReduce will be officially supported in 1.2.0 of PHPLib (https://jira.mongodb.org/browse/PHPLIB-53)
Until then, there is a completely usable workaround by using the command object as per https://docs.mongodb.com/php-library/current/upgrade/#mapreduce-command-helper

Example is here as well:

$database = (new MongoDB\Client)->selectDatabase('db_name');
$cursor = $database->command([
    'mapReduce' => 'collection_name',
    'map' => new MongoDB\BSON\Javascript('...'),
    'reduce' => new MongoDB\BSON\Javascript('...'),
    'out' => 'output_collection_name',
]);

$resultDocument = $cursor->toArray()[0];

You can also use MapReduce via Doctrine (http://docs.doctrine-project.org/projects/doctrine-mongodb-odm/en/latest/reference/map-reduce.html), but that is using legacy and a shim. So probably not a good choice for a new project.

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