title: MongoDB 3.0 and mongoDB 2.2
body: <p>I create NodeJS V8 app and use mongoDB local server. </p>
  
  <p>I had mongoDB version ^2.2.34 and connect to DB </p>
  
  <pre><code>    let mongodb = require('mongodb');
      let mongoClient = mongodb.MongoClient;
  
      let connection = mongoClient.connect('mongodb://localhost:27017/Test');
  
      let getCollection = function (c) {
          return connection.then(function (db) {
              return db.collection(c);
          });
      };
  </code></pre>
  
  <p>It worked. I update my mongoDB version to ^3.0.1 and have error</p>
  
  <pre><code>(node:16320) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): TypeError: db.collection is not a function
  </code></pre>
  
  <p>Why in new version it isn't work and how I can change code?</p>