Step 4: Declaring the Workflow Event

In this step, you will declare the workflow event that triggers the transition from the PendingPayment workflow state to the ReadyForAssignment workflow state, define an event handler for this event, and register the workflow event handler in the screen configuration. You will also define the transition triggered by the workflow event.

Do the following:

In the RSSVWorkOrder DAC, declare a class that contains the new workflow event, as the following code shows.
```
        public class WorkflowEvents : 
            PXEntityEvent<ARRegister>.Container<WorkflowEvents>
        {
            public PXEntityEvent<ARRegister> InvoiceGotPrepaid = null!;
        }
```
Tip: Make sure that you have added the PX.Data.WorkflowAPI using directive.
In the RSSVWorkOrderEntry graph, declare an event handler for the InvoiceGotPrepaid workflow event, as the following code shows.
```
        public PXWorkflowEventHandler<RSSVWorkOrder, ARRegister> OnInvoiceGotPrepaid
            = null!;
```

In the RSSVWorkOrderEntry_Workflow class, bind the OnInvoiceGotPrepaid workflow event handler to the InvoiceGotPrepaid workflow event in the screen configuration: In the lambda expression for the WithHandlers method, add the handler, as the following code shows.

                    handlers.Add(handler => handler
                        .WithTargetOf<ARRegister>()
                        .OfEntityEvent<RSSVWorkOrder.WorkflowEvents>(
                            workflowEvent => workflowEvent.InvoiceGotPrepaid)
                            .Is(graph => graph.OnInvoiceGotPrepaid)
                            .UsesPrimaryEntityGetter<
                                SelectFrom<RSSVWorkOrder>.
                                Where<RSSVWorkOrder.invoiceNbr
                                .IsEqual<ARRegister.refNbr.FromCurrent>>>());

In the GetPendingPaymentBehavior private static method, add the workflow event handler by using the WithEventHandlers method, as the following code shows.
```
            .WithEventHandlers(handlers =>
            {
                handlers.Add(graph => graph.OnInvoiceGotPrepaid);
            });
```
In the lambda expression for the WithTransitions method, declare the transition from the PendingPayment workflow state to the ReadyForAssignment workflow state in the transitions.AddGroupFrom<States.pendingPayment> group, as the following code shows.
```
                            transitionGroup.Add(transition =>
                                transition.To<States.readyForAssignment>()
                                .IsTriggeredOn(graph => graph.OnInvoiceGotPrepaid));
```
Save your changes.