Solved API for Adding a Port on a Group Node?

Hi,

Is there an API way to add port on a group node, and consequently, rename them?
So far the only examples I can find is modifying an existind node.

I did try using AddPort method. But it gives me an error of
ValueError: You can't add a port directly to node group@L8BzdBtMNh1sWN7TnpEXFD.

Here's what I'm trying to do:

Hi,
you have the function CreateInputPort that will help you to create that port.

You could use this code #addedPort = groupRoot.GetInputs().AddPort("newID") The difference is that the port will be identified only with the ID you passe as the argument of AddPort. CreateInputPort will create for you a hash and will add it to the port's ID creating something like passedID@Hashxxxxxx

There is no type as the port is just streaming the data. As you can still specify the data using the Resource editor, i will ask the dev if you can do it programmatically to force the type of the port.

Here an example that will group the selected nodes in the selected material and add an input port to the group.

import c4d
import maxon


def main():
    # Retrieve the selected BaseMaterial
    mat = doc.GetActiveMaterial()
    if mat is None:
        raise ValueError("There is no selected BaseMaterial")

    # Retrieve the reference of the material as a node material.
    nodeMaterial = mat.GetNodeMaterialReference()
    if nodeMaterial is None:
        raise ValueError("Cannot retrieve node material reference")

    # Retrieve the current node space Id
    nodespaceId = c4d.GetActiveNodeSpaceId()

    # Retrieve the Nimbus reference for a specific node space
    nimbusRef = mat.GetNimbusRef(nodespaceId)
    if nimbusRef is None:
        raise ValueError("Cannot retrieve the nimbus ref for that node space")

    # Retrieve the graph corresponding to that node space.
    graph = nimbusRef.GetGraph()
    if graph is None:
        raise ValueError("Cannot retrieve the graph of this nimbus ref")

    # Get the root of the GraphNode
    root = graph.GetRoot()

    # Retrieve all nodes, child of the root node
    nodes = []
    root.GetChildren(nodes, maxon.NODE_KIND.NODE)

    # Create a list of the selected ones.
    selectedNodes = []
    maxon.GraphModelHelper.GetSelectedNodes(graph, maxon.NODE_KIND.NODE, selectedNodes)
 
    # Group all the selected nodes in an empty node.
    groupRoot = maxon.GraphNode()

    # To modify a graph, modification must be done inside a transaction. After
    # modifications are done, the transaction must be committed.
    with graph.BeginTransaction() as transaction:
        groupRoot = graph.MoveToGroup(groupRoot, maxon.Id("idOfMyGroup"), selectedNodes)
        maxon.GraphModelHelper.CreateInputPort(groupRoot, "someid", "new port name")
        transaction.Commit()

    # Pushes an update event to Cinema 4D
    c4d.EventAdd()


if __name__ == "__main__":
    main()

Cheers,
Manuel

@manuel

Thanks for the illustration code. I'm trying to supplement it by connecting the group ports and node ports but I'm having problem doing so.

See sample code with comments.

    value = selectedNodes[0] # assuming the selected node is a value node

    with graph.BeginTransaction() as transaction:
        groupRoot = graph.MoveToGroup(groupRoot, maxon.Id("idOfMyGroup"), selectedNodes)
        maxon.GraphModelHelper.CreateInputPort(groupRoot, "someid", "new port name")
        

       print (groupRoot.GetInputs().FindChild("someid") ) # returns null instead of a node object
       print (groupRoot.GetOutputs().FindChild("someid") ) # returns null instead of a node object
       
       print (value.GetInputs().FindChild("in")) # returns an error of ValueError: Node with path type@KX8Pk7tsBJgq7AjxVnYQLZ doesn't exist any longer. Not sure why the path matters considering I'm already storing the actual node in a variable (i.e. value)

Thanks for looking at my problem.

The function CreateInputPort will return the new port. Its complete ID will be something like someid@BSMjOUqqO13ufL3qExOL5B where the part after the @ make it unique. If you use FindChild only using "someid" it will not find the port.

    with graph.BeginTransaction() as transaction:
        groupRoot = graph.MoveToGroup(groupRoot, maxon.Id("idOfMyGroup"), selectedNodes)
        newPort = maxon.GraphModelHelper.CreateInputPort(groupRoot, "someid", "new port name")
        value = []
        maxon.GraphModelHelper.FindNodesByAssetId(graph,"net.maxon.node.type", True, value)
        valueNode = value[0]
        inputNode = valueNode.GetInputs().FindChild("in")
        print (inputNode, newPort)
        newPort.Connect(inputNode)
        transaction.Commit()

Defining the ports' type added to the group is not possible. You need to use SetType that is not available.

Cheers,
Manuel

@manuel

Thanks for the illustration. Works as expected.

When you have this statement:

        maxon.GraphModelHelper.FindNodesByAssetId(graph,"net.maxon.node.type", True, value)
        valueNode = value[0]
        inputNode = valueNode.GetInputs().FindChild("in")

I'm guessing this part of my previous code is no longer working and so we need to reestablish the variable again.

value = selectedNodes[0] 

Anyhow, thanks again.
Closing this thread now :)