OPC UA node huge list read/subscribe

[Merlino]

Hello!

I am developing an application that has to monitor the value changes of a huge list of Opc Ua nodes.

I have already made a tiny test that works correctly:

auto* testNode = m_client->node("ns=3;i=1001");

if (testNode)
{
  connect(testNode, &QOpcUaNode::dataChangeOccurred, this, [](QOpcUa::NodeAttribute attribute, QVariant value)
  {
    // How can I retrieve the nodeId of who generated the event here?
    qInfo().nospace().noquote() << "Attribute " << attribute << " changed " << value ;
  });

  m_testNode->enableMonitoring(QOpcUa::NodeAttribute::Value, QOpcUaMonitoringParameters(100));
}

In this case, however, it is necessary to have a unique slot / lambda for each node. Instead, I would like to focus the management of all changes on a single slot for all monitored nodes.

The problem is that the "dataChangeOccurred" event does not provide information on the node that raised it.

Having a single slot for all nodes: how could I know who generated the event?

[JonB]

@Merlino
Maybe I misunderstand. But testNode is the one which emitted the signal, so why don't you pass that to your lambda? Is that not what you are asking for?

[fcarney]

connect(testNode, &QOpcUaNode::dataChangeOccurred, this, [testNode](QOpcUa::NodeAttribute attribute, QVariant value)
  {
    // How can I retrieve the nodeId of who generated the event here?
    qInfo().nospace().noquote() << "Attribute " << attribute << " changed " << value ;
    // do stuff with testNode?
  });

[Merlino]

@JonB I would like to do something like this:

for(auto nodeData : listOfNodesToBeSubsribed )
{
  auto* node = m_client->node(nodeData.nodeID);
  
  if (node)
  {
    m_subscribedNodesList.insert(node);
  
    connect(node, &QOpcUaNode::dataChangeOccurred, this, [this, nodeData](QOpcUa::NodeAttribute attribute, QVariant value)
    {
  	this->DoStuffWithNode(nodeData, value);
    });
  
    node->enableMonitoring(QOpcUa::NodeAttribute::Value, QOpcUaMonitoringParameters(100));	 
  }
}

but written like this I doubt it will work...

[jsulm]

@Merlino said in OPC UA node huge list read/subscribe:

but written like this I doubt it will work

Why not? Did you try?

[Merlino]

@jsulm yes, it works! :)