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Let's say you have been asked to build a user interface for data clerks that only enter a single type of orders for patients in a specific care setting implying that when the user is logging into the system they choose an order type and a care setting, we know that the care setting and order type are always going to be the same for the duration of the user's http session. Let's also say that some of the orders they enter into the system already have pre-generated order numbers and you are required to let them enter those order numbers. How do you address this to simplify your code? This is when an OrderContext becomes relevant. You can initialize the care setting and order type upon user login, set them on the OrderContext object which you can cache in the http session. As for the pre-generated order numbers, you could write a form in the UI backed up by a Servlet or Controller that reads and sets the next order number as an order context attribute with a specific known key, along side it you also write an order number generator that knows how look up the next order number from the order context by its key. Lets have a code example to demonstrate this.

Code Block

language	java
theme	Eclipse
language	java
title	LoginServlet
linenumbers	true

public class LoginServlet extends HttpServlet {
    
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		//process login....

		String careSettingId = request.getParameter("careSettingId");
		String orderorderTypeIdId = request.getParameter("orderTypeId");
		OrderService orderService = Context.getOrderService();
		OrderContext orderContext = new OrderContext();
		orderContext.setCareSetting(orderService.getCareSetting(careSettingId));		
		orderContext.setOrderType(orderService.getOrderType(orderTypeId));

		request.getSession().setAttribute("orderContext", orderContext);

		 //Proceed......
	}
}

Code Block

language	java
theme	Eclipse	language	java
title	OrderServlet
linenumbers	true

public class OrderServlet extends HttpServlet {
    
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		OrderService orderService = Context.getOrderService();
		Order order = new Order();
		order.setPatient(Context.getPatientService().getPatient(request.getParameter("patientId")));
		order.setConcept(Context.getConceptService().getConcept(request.getParameter("conceptId")));
		order.setOrderer(Context.getProviderService().getProvider(request.getParameter("providerId")));
		order.setEncounter(Context.getEncounterService().getEncounter(request.getParameter("encounterId")));
	    
        //Get the order context and pass it to the API when saving the order
		OrderContext orderContext = request.getSession().getAttribute("orderContext");
		//This will later be looked up by our order number generator
		orderContext.setAttribute("pregeneratedOrderNumber", request.getParameter("userEnteredOrderNumber"));

        try{ 
			orderService.saveOrder(order, orderContext);
		}finally{
			orderContext.removeAttribute("pregeneratedOrderNumber");
        }

		//Proceed...
	}
}

Code Block

language	java
theme	Eclipse	language	java
title	MyOrderNumberGenerator
linenumbers	true

@Component("myOrderNumberGenerator")
public class MyOrderNumberGenerator implements OrderNumberGenerator {
    
    @Override
    public String getNewOrderNumber(OrderContext orderContext) {
		String nextOrderNumber = null;
		//Use the pre-generated one entered by the user if any which was added to
		//the orderContext by the OrderServlet class below that handles the request
		if(orderContext != null){
			nextOrderNumber = orderContext.getAttribute("pregeneratedOrderNumber"); 
		}

		//User didn't specify one, generate it
        if(nextOrderNumber == null){
			.......
		}
			
		return nextOrderNumber;
    }
}

...

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