gistfile1.cs

    public static class EntityItemExtension
    {
        public static TEntity GetById<TEntity>(this IEnumerable<TEntity> source, int id)
            where TEntity : class, IEntityItem
        {
            return source.First(e => e.Id.Equals(id));
        }

        public static void Save<TEntity>(this TEntity entity)
            where TEntity : class, IEntityItem
        {
            Table<TEntity> da = PALDataContext.Context.GetTable<TEntity>();

            if (entity.Id > 0)
                da.Attach(entity, true);

            else
                da.InsertOnSubmit(entity);

            da.Context.SubmitChanges();
        }

        public static void Delete<TEntity>(this TEntity entity)
            where TEntity : class, IEntityItem
        {
            Table<TEntity> da = PALDataContext.Context.GetTable<TEntity>();

            da.Attach(entity);
            da.DeleteOnSubmit(entity);
            da.Context.SubmitChanges();
        }
    }