Taking sum of “column” in MongoDB

Question

In MySQL, I would simply go \"SELECT sum(pts) FROM table\" to get the sum of the pts column on the table. However, I am converting this application to MongoDB and cannot fin

Answer 1

Utilizing MongoDB's new Aggregation Framework:

$result = $db->command(array(

    'aggregate' => 'COLLECTION_NAME',

    'pipeline'  => array(
        // Match:
        // We can skip this in case that we don't need to filter 
        // documents in order to perform the aggregation
        array('$match' => array(
            // Criteria to match against
        )),

        // Group:
        array('$group'  => array(
            // Groupby fields:
            '_id'       => "$fieldname1, $fieldname2, $or_empty, $etc",
            // Count:
            'count'     => array('$sum' => 1),
            // Sum:
            'type_sum'  => array('$sum' => '$type'),
        ))

        // Other aggregations may go here as it's really a PIPE :p

    ),
));