Creating node with flow output port

JS_KN · July 23, 2021, 8:56am

I have a node that retrieves some information and pushes it as a flow variable to the further workflow. This node does not do anything with data, so it has no use for input or output ports.
I can activate the flow variable ports at the top of the node and connect them to the remaining workflow, but I would like to have my flow output as an explicit and documentable output port of flow type, just like the standard configuration nodes. Is this possible for custom nodes?

grafik

gab1one · July 23, 2021, 9:33am

Hi @JS_KN,

Yes that is possible, you need to use the more generic constructor in NodeModel:

github.com

knime/knime-core/blob/master/org.knime.core/src/eclipse/org/knime/core/node/NodeModel.java#L277

    
      
              Arrays.fill(portTypes, BufferedDataTable.TYPE);
              return portTypes;
          }
          
          
/**
           * Creates a new model with the given number (and types!) of input and
           * output types.
           * @param inPortTypes an array of non-null in-port types
           * @param outPortTypes an array of non-null out-port types
           */
          protected NodeModel(final PortType[] inPortTypes,
                  final PortType[] outPortTypes) {
              // create logger
              m_logger = NodeLogger.getLogger(this.getClass());
          
          
    // init message listener array
              m_warningListeners =
                             new CopyOnWriteArraySet<NodeModelWarningListener>();
          
          
    // check port types of validity and store them
              if (inPortTypes == null) {

Take a look at this example from knime-python:

github.com

knime/knime-python/blob/master/org.knime.python2.nodes/src/org/knime/python2/nodes/conda/CondaEnvironmentPropagationNodeModel.java#L175

    
      
          
          
private final SettingsModelString m_validationMethodModel = createEnvironmentValidationMethodModel();
          
          
private final SettingsModelString m_outputVariableNameModel = createOutputVariableNameModel();
          
          
private final SettingsModelBoolean m_preserveIncompleteEnvsModel = createPreserveIncompleteEnvsModel();
          
          
private final SettingsModelString m_sourceOsModel = createSourceOsModel();
          
          
public CondaEnvironmentPropagationNodeModel() {
              super(new PortType[0], new PortType[]{FlowVariablePortObject.TYPE});
          }
          
          
@Override
          protected void saveSettingsTo(final NodeSettingsWO settings) {
              m_environmentNameModel.saveSettingsTo(settings);
              m_packagesConfig.saveSettingsTo(settings);
              m_validationMethodModel.saveSettingsTo(settings);
              m_outputVariableNameModel.saveSettingsTo(settings);
              m_preserveIncompleteEnvsModel.saveSettingsTo(settings);
              m_sourceOsModel.saveSettingsTo(settings);

best,
Gabriel

JS_KN · July 23, 2021, 11:10am

Thanks a lot, works now

system · July 30, 2021, 11:10am

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.