title: mongoose do not return saved document in callback
body: <p>I am trying to save a new record using mongoose. I am not getting the saved document in the callback.</p>
  
  <pre><code> app.post("/register",(req,res) =&gt; {
      let userData = req.body;
      let user = new User(userData)
      user.save().then((err,doc) =&gt; {
          res.json({"success":true,"data":doc});
          console.log(doc);
      })    
  });
  </code></pre>
  
  <p>I am getting doc:1. While I should get the whole document. Please help me.</p>
  
  <pre><code>  "dependencies": {
      "body-parser": "^1.18.2",
      "crypto-js": "^3.1.9-1",
      "express": "^4.15.5",
      "mongoose": "^4.11.13"
    }
  </code></pre>