code: function(fields, template_name) {
      var fields_sanitized = [];
      if (fields && fields.length > 0) {
        var self = this;
        fields_sanitized = _.map(fields, function(field,i) {
          // Return whole attribute sanitized
          return self._sanitizeField(field, template_name, field.index || i);
        });
      }
      return fields_sanitized;
    }
docs: Convert values to string unless value is NULL