code: function (projection = '') {
  
        //prepare projections
        let fields = _.compact(projection.split(','));
        fields = _.map(fields, _.trim);
        fields = _.uniq(fields);
        const accumulator = {};
  
        _.forEach(fields, function (field) {
  
          //if exclude e.g -name
          if (field[0] === '-') {
            accumulator[field.substring(1)] = 0;
          }
  
          //if include i.e name
          else {
            accumulator[field] = 1;
          }
  
        });
  
        return accumulator;
      }
docs: parse comma separated fields into mongodb awase projections