code: function(value, attr, range, model) {
          if (!_.isString(value) || value.length < range[0] || value.length > range[1]) {
            return this.format(getMessageKey(this.msgKey, defaultMessages.rangeLength), this.formatLabel(attr, model), range[0], range[1]);
          }
        }
docs: Range length validator Validates that the value has to be a string and equal to or between the two numbers specified