Question

public class ScheduleRatesController
    {
        protected CoreDataManager dataManager;

        public ScheduleRatesController()
        {
            dataManager = new CoreDataManager();
        }

        // testing
        public ScheduleRatesController(CoreDataManager manager)
        {
            dataManager = manager;
        }

        public virtual void GetTranQuotesToFillRatesAndPayments(ref List<int> ids)
        {
            ids.AddRange(new List<int>());
        }
    }

So to give you guys some background, we’re splitting one DB query into a bunch of different ones, and we want subclasses to basically each take on a DB call for their GetTranQuotesToFillRatesAndPayments() method that represents it’s specific query.

What you see above is the base class I have. I made those two methods virtual as I plan on having subclasses override them to perform their own stuff. So one could be like:

public override void GetTranQuotesToFillRatesAndPayments(ref List<int> ids)
        {
            ids.AddRange(dataManager.GetLoanTranQuotes());
        }

and etc. My question is, is this the best/cleanest way to perform a pattern like this?

The code that calls this is going to contain a huge list of filtered id’s, that it’s going to need to fill by calling each classes call to GetTranQuotesToFillRatesAndPayments(). Let me know if this doesn’t make sense. I’m kind of getting turned off by the fact that I’m going to need to call the same method like 6 times, each on a different class. I think that might be messy in itself even though the goal of it was to make it clean. I don’t want to have something like this on the calling side:

List<int> ids = new List<int>();
ScheduleRatesController controller = new LoanController();
controller.GetTranQuotesToFillRatesAndPayments(ref ids);

controller = new TradeController();
controller.GetTranQuotesToFillRatesAndPayments(ref ids);

etc.

Let me know if you need any more background or info.

Thanks.

Answer 1

Several design remarks:

1. Using the ref keyword usually indicates design problems and should be avoided. There is no need to pass a reference value using the ref keyword (any List<T> is always passed by reference). Your program would work equally without it.

2. A better idea than passing your list to the method would be to return your data from the method, and allow callers to decide what to do with it. Maybe you will only want to find a single value at some other place in your program, and creating a new list is an overkill. Also, you should try to add as little functionality as possible to each class (Single Responsibility Principle), and your class is right now responsible for fetching the data and deciding how it should be stored.

3. Naming: your method name is really complex. Also, the name “controller” doesn’t usually represent an object responsible for fetching data.

4. On the other hand, you have a CoreDataManager class (btw, Manager is a bad suffix for any class), which appears to contain a bunch of methods which return various data. What is the need for ScheduleRatesController then? Does it only copy this to a list?

5. Business logic should be separated from your Data access layer. You should consider using Repository pattern, or similar (check this answer, for example), to ensure that your data class only fetches the data from the DB.

If you have several classes which need to fulfill a certain contract, start by creating the interface which they need to implement. Don’t think about reusing code at this time. Your code, for example, forces all subclasses to use the CoreDataManager, while one day it may turn out that a certain “controller” might need to be composed of different objects.