title: Mongoose: return only values
body: <p>I am using Mongoose to query my User schema, which contains:</p>
  
  <pre><code>var usersSchema = new Schema( 
      {
          email : String,
          regId : { type : String , default : '' },
          lastName : { type : String , default : '' },
          ...
      });
  </code></pre>
  
  <p>I need to get <code>getId</code> property values for the array of emails i have. Currently i am trying to do:</p>
  
  <pre><code>db.model('users').find( { email : { $in : arrUsers } }, { regId : true, _id : false }, function (err, res) { ... }
  </code></pre>
  
  <p>I receive this array: <code>[{ regId : "..." }, { regId : "..." }]</code> .</p>
  
  <p>What i want to receive: <code>{ "...", "..." }</code> .</p>
  
  <p>Is there an easy way to do this? Thanks a lot !!!</p>
  
  <p>EDIT: I am interested in doing the for loop on the database side...</p>