Interface for a CRM system

Question

I have a CRM system that has Notes, Payments, DairyEvents and anything else that needs to be bolt on over time.

I created an ITimeline interface that has a datetime and message method and implemented them on those models.

This is the simplest form of code I have started with:

public static List<Interfaces.ITimeline> GetAll(long personID)
{
 List<Interfaces.ITimeline> timelineEvents = new List<Interfaces.ITimeline>();
 timelineEvents.AddRange(Controllers.FollowUp.GetAll(personID));
 //add more to the list as the system grows
 return timelineEvents;
}

That is fine, as long as one of the controllers doesn't throw and error, then the whole Interface collapses. I had something similar happen on a another project, production environment, where a single provider went haywire due a bug on their system, amongst several other providers that were being interfaced with and worked fine. It wouldn't be so bad if it didn't crash all 600+ sites, just because of that mistake somebody else made.

I don't want to do try catches around every single addrange - I think that is just cluttering. Also, with integration like that, you build things to work, but exceptions happens here and there.

What is a proper way of taking data from various sources, controllers or integration, adding them to a collection of items for the interface? That way, if something fails in the middle, it won't bring down the entire page, or even worse, the whole framework.

Answer 1

The error should be caught where it occurs, namely in the controller. If possible try to implement something like this

TimelineEventCollection personTimelineEvents; // Change to the appropriate collection type.
if (Controllers.FollowUp.TryGetAll(personID, out personTimelineEvents)) {
 timelineEvents.AddRange(personTimelineEvents);
}

The advantage of this approach is that the error does not get swallowed up silently by some try-catch-statement. You get a Boolean return value from TryGetAll telling you if all went right. At the same time the basic error handling happens in a low level method and not in your list filling routine.

If you cannot alter the Controllers.FollowUp class, you can still write an extension method giving you the same functionality.

• Piotr Kula: That is SOLID advice! Defiantly a great approach, I use TryGet almost daily and never thought of doing that on my own code! Thanks +1