Add relations to a Custom C# node

[!NOTE] To add logic to a node, you must create a Custom C# node and add ports. [!include[vs-tasks-note-end](./snippets/custom-c-nodes/vs-tasks-note-end.md)]

After you add ports and add logic to a node, relations help Visual Scripting correctly display a Custom C# node in a Script Graph.

To add relations to a node:

1. [!include[open-project-window](./snippets/vs-open-project-window.md)]

2. [!include[open-existing-external-code](./snippets/vs-open-existing-external-code.md)]

3. In your external editor, add relations in the format $RelationType$($Port1$, $Port2$), where $RelationType$ is the relation type you want to assign between the ports you specify as $Port1$ or $Port2$.

   For example, to assign relations to the previous example node:

    using System;
    using Unity.VisualScripting;
    using UnityEngine;
   
    public class MyNode : Unit
    {
    [DoNotSerialize]
    public ControlInput inputTrigger;
   
    [DoNotSerialize]
    public ControlOutput outputTrigger;
   
    [DoNotSerialize]
    public ValueInput myValueA;
   
    [DoNotSerialize]
    public ValueInput myValueB;
   
    [DoNotSerialize]
    public ValueOutput result;
   
    private string resultValue;
    protected override void Definition()
    {
        inputTrigger = ControlInput("inputTrigger", (flow) =>
        {
            resultValue = flow.GetValue<string>(myValueA) + flow.GetValue<string>(myValueB) + "!!!";
            return outputTrigger;
        });
        outputTrigger = ControlOutput("outputTrigger");
        
        myValueA = ValueInput<string>("myValueA", "Hello ");
        myValueB = ValueInput<string>("myValueB", String.Empty);
        result = ValueOutput<string>("result", (flow) => resultValue);
        
        Requirement(myValueA, inputTrigger); //Specifies that we need the myValueA value to be set before the node can run.
        Requirement(myValueB, inputTrigger); //Specifies that we need the myValueB value to be set before the node can run.
        Succession(inputTrigger, outputTrigger); //Specifies that the input trigger port's input exits at the output trigger port. Not setting your succession also dims connected nodes, but the execution still completes.
        Assignment(inputTrigger,result);//Specifies that data is written to the result string output when the inputTrigger is triggered.
    }
    }

   For more information on relation types, see Custom C# nodes.

4. [!include[save-script](./snippets/vs-save-script.md)]

5. [!include[return-unity](./snippets/vs-return-unity.md)]

6. Do one of the following:

   • [!include[open-graph-w-node](./snippets/custom-c-nodes/vs-open-graph-w-node.md)].
   • [!include[ff-add-node](./snippets/custom-c-nodes/vs-ff-add-node.md)]

7. In the Graph toolbar, enable Relations.

   Visual Scripting displays the relations you assigned to the Custom C# node. If you used the previous code sample, the node's relations might look like the following image:

   

Next steps

After you add relations to a node, you can choose to add documentation or customize the node with attributes.