Question

I’ve run into a bit of a problem with EF looking for the best practice for this problem:

public void TestEntityFramework_UOWImplementation()
{
    using (UnitOfWorkInventory uow = new UnitOfWorkInventory())
    {
        IMaterialRepository repos = new MaterialRepository(uow);

        Material mat = GetMaterial("Mikes Material", 1);

        mat.CostPrice = 20;

        repos.InsertOrUpdate(mat);

        uow.Commit();
    }
}

private Material GetMaterial(string sku, int clientId)
{
    IMaterialRepository repos = new MaterialRepository(new UnitOfWorkInventory();

    return repos.Find(sku, clientId);

}

In the TestEntityFramework_UOWImplementation() method, its fine, i call create a scope for my unit of work.. and create a repository inside it.

But when i want to getMaterials() as below.. I have no access to the unit of work or the repository, unless i actually pass it as a parameter! This is clearly not particularly nice.

How do people get around this problem??

Thanks in advance!

Neil

Answer 1

If anyone was looking for a way around this, I done something a bit different.

I used a Dependency Injection framework (StructureMap) to handle all DI, so everytime i instantiate a repository it will retrieve the DBContext from the Service Locator of StructureMap. I also make the dbcontext scope to be for the duration of the request from the webserver.

The advantage here being that everytime i retrieve or inject a DBContext, it will retrieve the same context for the duration of the request meaning i can use this across multiple methods and class! I pass the interface type as a generic param to the constructor, meaning that i can point the repo as different contexts. Helpful in applications where there are lots of dbcontexts.

Repo Constructor Eg:

public class PurchaseOrderRepository<TDbContext> : GenericRepository<PurchaseOrder>, IPurchaseOrderRepository<TDbContext> where TDbContext : DbContext
{

        public PurchaseOrderRepository()
            : base((TDbContext)ObjectFactory.GetInstance<TDbContext>())
        {
        }
}   

Usage:

 //resolves the request scope InventoryContext... 
var pRepos = new PurchaseOrderRepository<IInventoryContext>();

and the structure map dependency looks like:

    For<IInventoryContext>().HttpContextScoped().Use<InventoryContext>();