(mongodb >=1.0.0)
MongoDB\Driver\WriteResult::getWriteConcernError — Returns any write concern error that occurred
この関数にはパラメータはありません。
   Returns a MongoDB\Driver\WriteConcernError if a write
   concern error was encountered during the write operation, and null
   otherwise.
  
例1 MongoDB\Driver\WriteResult::getWriteConcernError() example
<?php
$manager = new MongoDB\Driver\Manager("mongodb://rs1.example.com,rs2.example.com/?replicaSet=myReplicaSet");
$bulk = new MongoDB\Driver\BulkWrite;
$bulk->insert(['x' => 1]);
$writeConcern = new MongoDB\Driver\WriteConcern(2, 1);
try {
    $manager->executeBulkWrite('db.collection', $bulk, ['writeConcern' => $writeConcern]);
} catch(MongoDB\Driver\Exception\BulkWriteException $e) {
    var_dump($e->getWriteResult()->getWriteConcernError());
}
?>上の例の出力は、 たとえば以下のようになります。
object(MongoDB\Driver\WriteConcernError)#6 (3) {
  ["message"]=>
  string(33) "waiting for replication timed out"
  ["code"]=>
  int(64)
  ["info"]=>
  object(stdClass)#7 (1) {
    ["wtimeout"]=>
    bool(true)
  }
}
