Singularity/Library/PackageCache/com.unity.visualscripting@1.8.0/Documentation~/vs-create-custom-node-add-relations.md

Add relations to a Custom C# node

Note

To add logic to a node, you must create a Custom C# node and add ports. [!includevs-tasks-note-end]

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. [!includeopen-project-window]

2. [!includeopen-existing-external-code]

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. [!includesave-script]

5. [!includereturn-unity]

6. Do one of the following:

   • [!includeopen-graph-w-node].
   • [!includeff-add-node]

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.