title: Mongoose deep population (specific field)
body: <p>I have three models. And i need to get the admin group name of a user</p>
  
  <p><strong>User</strong></p>
  
  <pre><code>  var userSchema = new mongoose.Schema({
      // ...
      roles: {
        admin: { type: mongoose.Schema.Types.ObjectId, ref: 'Admin' }, // path 1
      },
   });
  </code></pre>
  
  <p><strong>Admin</strong></p>
  
  <pre><code>  var adminSchema= new mongoose.Schema({
      // ...
      groups: [{ type: String, ref: 'AdminGroup' }], // path 2
    });
  </code></pre>
  
  <p><strong>AdminGroup</strong></p>
  
  <pre><code>  var adminGroupSchema = new mongoose.Schema({
      // ...
      name: { type: String, default: '' }, // need to get this field
    });
  </code></pre>
  
  <p>In Mongoose</p>
  
  <pre><code>User.findById(req.user._id)
      .populate({path: 'roles.admin', populate:{ path: 'groups'}})
        .exec(function (err, adminGroups) {...}
  </code></pre>
  
  <p>When I try to call in my template <code>{{adminGroups.name}}</code> it returns the <code>name</code> of <code>Admin</code> model, which also has a <code>name</code> field, instead of <code>AdminGroup</code> model.<br>
  I am usung Mongoose 4.9.0 so it must have support for deep population. 
  Thanks.</p>