PHPLIB mapReduce example

example.php

<?php

require_once 'vendor/autoload.php';

$client = new MongoDB\Client;

$collection = $client->selectCollection('test', 'mr_example');
$collection->drop();
$collection->insertMany([
    ['x' => 1, 'y' => 1],
    ['x' => 1, 'y' => 2],
    ['x' => 1, 'y' => 3],
    ['x' => 2, 'y' => 4],
    ['x' => 2, 'y' => 5],
    ['x' => 3, 'y' => 6],
]);

// MongoDB\BSON\Javascript supersedes the legacy driver's MongoCode class
$map = new MongoDB\BSON\Javascript('function() { emit(this.x, this.y); }');
$reduce = new MongoDB\BSON\Javascript('function(key, values) { return Array.sum(values); }');

$database = $client->selectDatabase('test');

/* MongoDB\Database::command() always returns a cursor. For commands that return
 * a single document (such as mapReduce), we need to iterate on this cursor and
 * access the first result to obtain the logical command result.
 *
 * In the case of commands that return multiple documents via a command cursor,
 * (such as aggregate), we could immediately iterate on the returned cursor to
 * obtain those results. Internally, MongoDB still returns a single-document
 * result, but it only serves as an envelope for constructing a command cursor.
 * That is all handled internally by the driver.
 *
 * @see https://docs.mongodb.com/php-library/current/tutorial/commands/#view-command-results
 */
$cursor = $database->command([
    'mapReduce' => 'mr_example',
    'map' => $map,
    'reduce' => $reduce,
    'out' => ['inline' => 1],
]);

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

/* When we dump this value, you'll notice that the command result contains
 * instances of BSONDocument and BSONArray, both of which extend PHP's
 * ArrayObject class.
 *
 * By default, the driver converts BSON documents and arrays to PHP stdClass
 * objects and arrays, respectively. The library instead uses BSONDocument and
 * BSONArray clases for both types. These both differ from the legacy driver,
 * where BSON documents and arrays were always converted to PHP arrays.
 *
 * You can customize the driver and library behavior with a custom type map,
 * which can be specified on any of the core library objects (e.g. Client,
 * Database, Collection), as an option to Database::command(), or on the
 * MongoDB\Driver\Cursor object returned by Database::command().
 *
 * @see http://php.net/manual/en/mongodb-driver-cursor.settypemap.php
 * @see https://docs.mongodb.com/php-library/current/reference/bson/
 * @see https://docs.mongodb.com/php-library/current/reference/bson/#emulating-the-legacy-driver
 */
var_dump($commandResult);

out.txt

$ php example.php 
object(MongoDB\Model\BSONDocument)#23 (1) {
  ["storage":"ArrayObject":private]=>
  array(4) {
    ["results"]=>
    object(MongoDB\Model\BSONArray)#21 (1) {
      ["storage":"ArrayObject":private]=>
      array(3) {
        [0]=>
        object(MongoDB\Model\BSONDocument)#13 (1) {
          ["storage":"ArrayObject":private]=>
          array(2) {
            ["_id"]=>
            float(1)
            ["value"]=>
            float(6)
          }
        }
        [1]=>
        object(MongoDB\Model\BSONDocument)#10 (1) {
          ["storage":"ArrayObject":private]=>
          array(2) {
            ["_id"]=>
            float(2)
            ["value"]=>
            float(9)
          }
        }
        [2]=>
        object(MongoDB\Model\BSONDocument)#20 (1) {
          ["storage":"ArrayObject":private]=>
          array(2) {
            ["_id"]=>
            float(3)
            ["value"]=>
            float(6)
          }
        }
      }
    }
    ["timeMillis"]=>
    int(54)
    ["counts"]=>
    object(MongoDB\Model\BSONDocument)#22 (1) {
      ["storage":"ArrayObject":private]=>
      array(4) {
        ["input"]=>
        int(6)
        ["emit"]=>
        int(6)
        ["reduce"]=>
        int(2)
        ["output"]=>
        int(3)
      }
    }
    ["ok"]=>
    float(1)
  }
}