<?php

class Book implements MongoDB\BSON\Persistable {
    function bsonSerialize() {
        $data = get_object_vars($this);
        return $data;
    }
    function bsonUnserialize(array $data) {
        foreach ($data as $name => $value) {
            $this->{$name} = $value;
        }
    }
}

class Page implements MongoDB\BSON\Persistable {
    function bsonSerialize() {
        $data = get_object_vars($this);
        return $data;
    }
    function bsonUnserialize(array $data) {
        foreach ($data as $name => $value) {
            $this->{$name} = $value;
        }
    }
}

// Aux
$manager = new MongoDB\Driver\Manager('mongodb://127.0.0.1:27017');
$bulk = new MongoDB\Driver\BulkWrite;
$wc = new MongoDB\Driver\WriteConcern(MongoDB\Driver\WriteConcern::MAJORITY);
$collection = 'db.books';

// Delete previous entries
$bulk->delete([], ['limit' => 0]);
$manager->executeBulkWrite($collection, $bulk, $wc);

// Create
$book = new Book();
$book->title = 'Unnameable';
$book->pages = [];
$page1 = new Page();
$page1->content = 'Lorem ipsum';
$book->pages[] = $page1;
$result = $bulk->insert($book);
$result = $manager->executeBulkWrite($collection, $bulk, $wc);

// Read
$query = new MongoDB\Driver\Query(['title' => $book->title]);
$cursor = $manager->executeQuery($collection, $query);
$bookAfterInsert = $cursor->toArray();

// hack to make update work properly
$book = $bookAfterInsert[0];

// Update
$book->description = 'An interesting document';
$page2 = new Page();
$page2->content = 'Dolor sit amet';
$book->pages[] = $page2;
$bulk->update(['title' => $book->title], $book);
$manager->executeBulkWrite($collection, $bulk, $wc);

// Read (again)
$query = new MongoDB\Driver\Query(['title' => $book->title]);
$cursor = $manager->executeQuery($collection, $query);
$bookAfterUpdate = $cursor->toArray();
var_dump($bookAfterUpdate[0]);

object(Book)#%d (%d) {
  ["_id"]=>
  object(MongoDB\BSON\ObjectID)#%d (%d) {
    ["oid"]=>
    string(24) "%s"
  }
  ["__pclass"]=>
  object(MongoDB\BSON\Binary)#%d (%d) {
    ["data"]=>
    string(4) "Book"
    ["type"]=>
    int(%d)
  }
  ["title"]=>
  string(10) "Unnameable"
  ["pages"]=>
  array(2) {
    [0]=>
    object(Page)#%d (%d) {
      ["__pclass"]=>
      object(MongoDB\BSON\Binary)#%d (%d) {
        ["data"]=>
        string(4) "Page"
        ["type"]=>
        int(%d)
      }
      ["content"]=>
      string(11) "Lorem ipsum"
    }
    [1]=>
    object(Page)#%d (%d) {
      ["__pclass"]=>
      object(MongoDB\BSON\Binary)#%d (%d) {
        ["data"]=>
        string(4) "Page"
        ["type"]=>
        int(%d)
      }
      ["content"]=>
      string(14) "Dolor sit amet"
    }
  }
  ["description"]=>
  string(23) "An interesting document"
}

object(Book)#20 (5) {
  ["_id"]=>
  object(MongoDB\BSON\ObjectID)#15 (1) {
    ["oid"]=>
    string(24) "56a0591c5853e9198118c281"
  }
  ["__pclass"]=>
  object(MongoDB\BSON\Binary)#16 (2) {
    ["data"]=>
    string(4) "Book"
    ["type"]=>
    int(128)
  }
  ["title"]=>
  string(10) "Unnameable"
  ["pages"]=>
  array(2) {
    [0]=>
    object(Page)#18 (2) {
      ["__pclass"]=>
      object(MongoDB\BSON\Binary)#17 (2) {
        ["data"]=>
        string(4) "Page"
        ["type"]=>
        int(128)
      }
      ["content"]=>
      string(11) "Lorem ipsum"
    }
    [1]=>
    object(stdClass)#19 (1) {
      ["content"]=>
      string(14) "Dolor sit amet"
    }
  }
  ["description"]=>
  string(23) "An interesting document"
}