Refreshing cache in Dependency Injection

Question

I am new to development in C# so still figuring a few things out. I am trying to stick to good design principals so as to keep my code maintainable. So doing I am building a Line of Business application using the MVVM and Factory patterns. I am also using Dependency Injection (Unity).

My question is about refreshing the data cache created with Dependency Injection. When I create my View Model the data cache is loaded as follows:

_container.RegisterType<IRepo<Relation>, RelationRepo>(new TransientLifetimeManager());

My scenario is that I have a data presented to the users in a GridView. I have a multi user environment with dynamic information so it is possible that from time to time the data in the Cache becomes obsolete. This may result, as could be expected, in an DBConcurrency error from time to time. What I am grappling with is how to handle this in the correct manner. Should I abort the whole process and have the user reload the application thereby recreating the DI or is there an elegant way to refresh the cache and re-present the data after providing necessary information to user. Using the 2n'd option I could perhaps place a refresh button on the screen or a timed event to refresh data so user can see any variations in data.

So basically what I'm asking is how do I keep the Cache in sync with the underlying Data Base in real-time?

Thanks in advance.

Answer 1

Although its a while ago I thought i'd post the solution to my problem in case someone else is grappling with the concepts as I was.

The issue was that I was not properly disposing my ViewModel when I navigated away from the View (or if there was a DB Error). Therefor when I returned to the View the EF DBContext was still using the local store. i.e not Disposed.

I subsequently implemented the Prism Framework and implemented IRegionMemberLifetime on a base class from which all my ViewModels inherit. This causes the instance of the ViewModel placed in the Region Manager (IRegion) to be removed when it transitions from an activated to deactivated state.

My (pseudo) base class looks like this:

using Prism.Mvvm;
using Prism.Regions;

public MyBindableBase : BindableBase, IRegionMemberLifetime
{
    public virtual bool KeepAlive => false;
...
}