code: function get_wiring( req, res, next) {
  		req.wiring_collection.findOne({
  					user_id: req.current_user._id, 
  					_id: ObjectID.createFromHexString(req.param('id')) 
  			}, function(error, wiring) {
  				if(error) { throw error; }
  				req.wiring = wiring;
  				next();
  			});
  	}
docs: store the wiring document into req.wiring