ASP.Net Entity Framework Repository & Linq
- by Chris Klepeis
My scenario:
This is an ASP.NET 4.0 web app programmed via C#
I implement a repository pattern. My repositorys all share the same ObjectContext, which is stored in httpContext.Items. Each repository creates a new ObjectSet of type E. Heres some code from my repository:
public class Repository<E> : IRepository<E>, IDisposable
where E : class
{
private DataModelContainer _context = ContextHelper<DataModelContainer>.GetCurrentContext();
private IObjectSet<E> _objectSet;
private IObjectSet<E> objectSet
{
get
{
if (_objectSet == null)
{
_objectSet = this._context.CreateObjectSet<E>();
}
return _objectSet;
}
}
public IQueryable<E> GetQuery()
{
return objectSet;
}
Lets say I have 2 repositorys, 1 for states and 1 for countrys and want to create a linq query against both. Note that I use POCO classes with the entity framework. State and Country are 2 of these POCO classes.
Repository stateRepo = new Repository<State>();
Repository countryRepo = new Repository<Country>();
IEnumerable<State> states = (from s in _stateRepo.GetQuery()
join c in _countryRepo.GetQuery() on s.countryID equals c.countryID
select s).ToList();
Debug.WriteLine(states.First().Country.country)
essentially, I want to retrieve the state and the related country entity. The query only returns the state data... and I get a null argument exception on the Debug.WriteLine
LazyLoading is disabled in my .edmx... thats the way I want it.
