public interface IRepository<T, TPkType>
{
    IQueryable<T> Select();
    T SelectOnId(TPkType id);
    IQueryable<T> SelectPaged<TResult>(int pageIndex, int pageSize, Expression<Func<T, TResult>> sortExpression, bool isAscending);
    IQueryable<T> FindPaged<TResult>(int pageIndex, int pageSize, Expression<Func<T, bool>> findExpression, Expression<Func<T, TResult>> sortExpression, bool isAscending);
    IQueryable<T> Find(Expression<Func<T, bool>> expression);
    T Save(T item);
    void Delete(TPkType id);
}