(mongodb >=1.2.0)
MongoDB\Driver\WriteConcern::bsonSerialize — Returns an object for BSON serialization
This function has no parameters.
Returns an object for serializing the WriteConcern as BSON.
Example #1 MongoDB\Driver\WriteConcern::bsonSerialize() with majority write concern
<?php
$wc = new MongoDB\Driver\WriteConcern(MongoDB\Driver\WriteConcern::MAJORITY);
var_dump($wc->bsonSerialize());
echo "\n", MongoDB\BSON\toJSON(MongoDB\BSON\fromPHP($wc));
?>
The above example will output something similar to:
object(stdClass)#2 (1) {
  ["w"]=>
  string(8) "majority"
}
{ "w" : "majority" }
Example #2 MongoDB\Driver\WriteConcern::bsonSerialize() with wtimeout and journal
<?php
$wc = new MongoDB\Driver\WriteConcern(2, 1000, true);
var_dump($wc->bsonSerialize());
echo "\n", MongoDB\BSON\toJSON(MongoDB\BSON\fromPHP($wc));
?>
The above example will output something similar to:
object(stdClass)#2 (3) {
  ["w"]=>
  int(2)
  ["j"]=>
  bool(true)
  ["wtimeout"]=>
  int(1000)
}
{ "w" : 2, "j" : true, "wtimeout" : 1000 }