code: function(includeSearch) {
                  var activeFilterFields = _.chain(this.filterableFields)
                      .pick(function(fieldData) {
                          return !_.isNull(fieldData.value) && !_.isUndefined(fieldData.value);
                      })
                      .mapObject(function(data) {
                          return data.value;
                      });
                  if (!includeSearch) {
                      activeFilterFields = activeFilterFields.omit(PagingCollection.DefaultSearchKey);
                  }
                  return activeFilterFields.value();
              }
docs: Gets an object of currently active (applied) filters.  Excludes
  the active search by default.
  @param {bool} includeSearch - Whether search should be included
  in the result.
  @returns {Object} An object mapping the names of currently active
  filter fields to their values.