Step 4 (Optional): Specifying the Order of Transitions

Transitions are checked based on their order of declaration in code. To specify that a transition should be checked before or after another transition, you should call the PlaceBefore or PlaceAfter method,

In Step 3: Grouping Transitions and Adding Conditions to Transitions, you have defined the following transitions from the onHold workflow state:

• A transition to the readyForAssignment workflow state
• A transition to the pendingPayment workflow state

Suppose that you want to make sure that the transition to the pendingPaymentworkflow state is always checked before the transition to the readyForAssignment workflow state.

To explicitly specify this order of transitions, call the PlaceBefore method in the definition of the transition from the onHold workflow state to the pendingPayment workflow state, as the following code shows.

                    .WithTransitions(transitions =>
                    {
                        transitions.AddGroupFrom<States.onHold>(transitionGroup =>
                        {
                            transitionGroup.Add(transition => 
                                transition.To<States.readyForAssignment>()
                                .IsTriggeredOn(graph => graph.ReleaseFromHold)
                                .When(!conditions.RequiresPrepayment));
                            transitionGroup.Add(transition => 
                                transition.To<States.pendingPayment>()
                                .IsTriggeredOn(graph => graph.ReleaseFromHold)
                                .When(conditions.RequiresPrepayment)
                                .PlaceBefore(transition => 
                                    transition.To<States.readyForAssignment>()));
                        });
                    }))

In this code,you have called the PlaceBefore method after calling the When method. Notice that you have passed in a lambda expression as a parameter to the PlaceBefore method, and within it, you have specified transition.To<States.readyForAssignment>() as the transition before which you want the transition being defined to be checked.