text: function handler() {
      this.keys = this.props["keys"];
  
      for (var i=0;i<this.keys.length;i++) {
          var type = this.keys[i]["type"];
          if (!(type === 'boolean' || type === 'string' || type === 'integer' || type === 'long' || type === 'double' || type === 'float'))
              throw "Invalid property type: " + type;
      }
      
  }