title: Rails Mongoid `pluck` equivalent?
body: <p>In my Rails app I am using MongoID with a Elasticsearch river for text search. </p>
  
  <p>For <code>@devices_with_config = ConfigTextSearch.search params[:device_id]</code> 
  I want to extract just the <code>device_id</code> fields for the matching records in the query. In <code>mongoID 3.1.0</code> I could just use <code>Band.all.pluck(:name)</code>. But unfortunately, I am stuck with 3.0.23. </p>
  
  <p>I see there is a similar moped expression <code>collections[:bands].find.select(name: 1)</code>...but I am new to rails and can't figure out how I would use a moped expression in a controller or model. </p>
  
  <p>Any Ideas on how I can just extract the 'device_id' field in matches with MongoId?</p>