title: how to search for referenced document in mongoosejs
body: <p>I have two Schemas <code>Organization</code> and <code>Location</code>. On <code>Organization</code> Schema i have referenced the Location Schema:</p>
  
  <pre><code>Organization = new Schema({
    location: {
      type: Schema.ObjectId,
      ref: 'Location'
    } 
  });
  </code></pre>
  
  <p><code>Location</code> schema has fields like country,state, city, district etc.</p>
  
  <p>Now how would I search the <code>Organization</code> with specific country or state or city.</p>
  
  <p>What I have found in the Mongoose Document is this way:</p>
  
  <pre><code>Organization
  .find()
  .populate([{path:'location',select:'country state city district' },
   {/*other population paths*/}] /*Some constriants here*/).exec(function(err, orgs){
     console.log(orgs);
  });
  </code></pre>
  
  <p>How do I achieve this type of search. Are there any plugins available for this type of reference document search?</p>