code: function (req, res) {
      var self = this;
  
      var query = this.model.findOne({'_id': req.params[this.idName]});
  
      this.populateQuery(query, this.filterPopulations('show'));
  
      query.exec(function (err, document) {
        if (err) {
          return res.handleError(err);
        }
  
        if (!document) {
          return res.notFound();
        }
  
        return res.ok(self.getResponseObject(document));
      });
    }
docs: Get a single document. The requested document id is read from the request parameters
  by using the {@link CrudController#idName} property.
  @param {IncomingMessage} req - The request message object the id is read from
  @param {ServerResponse} res - The outgoing response object
  @returns {ServerResponse} A single document or NOT FOUND if no document has been found