How to use

getExpression

method

in

org.wso2.siddhi.query.api.execution.query.selection.OutputAttribute

  private static List<StreamColumn> convertOutputStreamColumns(List<OutputAttribute> outputAttributeList) {
    return outputAttributeList.stream().map(outputAttribute -> {
      StreamColumn streamColumn = new StreamColumn();
      streamColumn.setName(outputAttribute.getRename());
      streamColumn.setDescription(outputAttribute.getExpression().toString());
      return streamColumn;
    }).collect(Collectors.toList());
  }
}

/**
 * obtains information of all the user defined Functions.
 */
private void loadFunctionData(SiddhiApp siddhiApp, List<OutputAttribute> functionList, SiddhiAppElements
    siddhiAppElements, String appData) {
  for (FunctionDefinition functionDefinition : siddhiApp.getFunctionDefinitionMap().values()) {
    for (OutputAttribute app : functionList) {
      if (app.getExpression() instanceof AttributeFunction) {
        if (functionDefinition.getId().equals(((AttributeFunction) app.getExpression()).getName())) {
          String functionDefinitionStr = getDefinition(functionDefinition, appData);
          siddhiAppElements.setFunction(functionDefinition.getId());
          siddhiAppElements.setFunctionQuery(functionDefinitionStr);
          break;
        }
      }
    }
  }
}

  /**
   * Generates a SelectedAttribute object from the given Siddhi OutputAttribute
   * @param outputAttribute                   Siddhi OutputAttribute object
   * @return                                  SelectedAttribute object
   * @throws DesignGenerationException        Error while getting the definition of the OutputAttribute
   */
  private SelectedAttribute generateSelectedAttribute(OutputAttribute outputAttribute)
      throws DesignGenerationException {
    SelectedAttribute selectedAttribute =
        new SelectedAttribute(
            ConfigBuildingUtilities.getDefinition(outputAttribute.getExpression(), siddhiAppString),
            outputAttribute.getRename());
    preserveAndBindCodeSegment(outputAttribute, selectedAttribute);
    return selectedAttribute;

  }
}