检查mongodb collection 是否存在

exists

<?php
    $mongo = new MongoClient();
    $db = $mongo->dbName;
    $collection = $db->collectionName;
    
    $cursor = $collection->find($criteria, array('_id' => 1))->limit(1);
    
    if($coursor->count() == 0){
      exit('not exist');
    }
    
    exit('exits');