EntityFrameworkSession

public abstract class Entity 
{
  public int Id {get;set;}
}

public class EntityFrameworkSession : ISession
{
  private readonly DbContext context;
  
  public EntityFrameworkSession(DbContext context) 
  {
    this.context = context;  
  }
  
  public T SingleOrDefault<T>(int id) where T : Entity
  {
    return context.Set<T>().SingleOrDefault(x => x.Id == id);
  }
  
  public T FirstOrDefault<T>(Func<T, bool> predicate) where T : Entity
  {
    return context.Set<T>().FirstOrDefault(predicate);
  }
  
  public IQueryable<T> All<T>() where T : Entity
  {
    return context.Set<T>().AsQueryable()
  }
  
  public void Add<T>(T entity) where T : Entity 
  {
    context.Set<T>().Add(entity);
  }
  
  public void Commit() 
  {
    return context.SaveChanges()
  }
  
  public void Delete<T>(T entity) where T : Entity
  {
    context.Set<T>().Remove(entity);
  }
}

public class Customer : Entity
{
  public string Name {get;set;}
}

public class CustomerController : ApiController
{
  private readonly ISession session;

  public CustomerController(ISession session) 
  {
    this.session = session;
  }

  public Customer GetById(int id)
  {
    return session.SingleOrDefault<Customer>(id);
  }
}