K2Node notes

Posted on Apr 11, 2026

K2Node

Bare Minimum

UCLASS()
class UK2Node_MyNode : public UK2Node
{
	GENERATED_BODY()
public:
	virtual void AllocateDefaultPins() override;
	virtual FText GetNodeTitle(ENodeTitleType::Type TitleType) const override;
	virtual FText GetMenuCategory() const override;
	virtual void GetMenuActions(FBlueprintActionDatabaseRegistrar& ActionRegistrar) const override;
};

Creating pins

Default input exec pin:

	CreatePin(EGPD_Input, UEdGraphSchema_K2::PC_Exec, UEdGraphSchema_K2::PN_Execute);

Default output exec pin:

	CreatePin(EGPD_Output, UEdGraphSchema_K2::PC_Exec, UEdGraphSchema_K2::PN_Then);

UObject input pin with specific subclass:

    CreatePin(EGPD_Input, UEdGraphSchema_K2::PC_Object, UMyObject::StaticClass(), "MyObject");

void UK2Node_MyNode::GetMenuActions(FBlueprintActionDatabaseRegistrar& ActionRegistrar) const
{
	UClass* ActionKey = GetClass();
	if (ActionRegistrar.IsOpenForRegistration(ActionKey))
	{
		UBlueprintNodeSpawner* Spawner = UBlueprintNodeSpawner::Create(GetClass());
		check(Spawner);
		ActionRegistrar.AddBlueprintAction(ActionKey, Spawner);
	}
}

Disallow wiring the input pin

bool UK2Node_MyNode::IsConnectionDisallowed(
    const UEdGraphPin* MyPin,
    const UEdGraphPin* OtherPin,
    FString& OutReason) const
{
    if (MyPin->PinName == FName("MyPinName"))
    {
        OutReason = TEXT("Cannot wire this pin, must be set directly");
        return true;
    }

    return Super::IsConnectionDisallowed(MyPin, OtherPin, OutReason);
}

Reacting to value change

Implement the following function if you need to react to a value change on a specific pin:

UK2Node::PinDefaultValueChanged(UEdGraphPin* Pin);