title: get day of the week from mongodb datetime query
body: <p>I am constructing a database where I might want to query a day of the week. Is it possible to use mongodb to query days in the week in a datetime (or utc timestamp) field? </p>
  
  <p>Something like; get every object that has a datetime that was on a monday. </p>
  
  <p>If it is not possible then the alternative seems to create dummy variables in the collection that show what day of the week it was. Preferably I would like to only query the datetime object for this as this would keep the database smaller. </p>