联表查询，判断追加条件，对集合分页

public ActionResult Index(string titleName, string nickName, int pageIndex = 1)        {            var data = from m in _db.AppArticleComment                       join o in _db.AppArticle on m.ArticleId equals o.ArticleId                       where (string.IsNullOrEmpty(nickName) ? true : m.NickName == nickName)//在此判断加条件，当变量值null需要转为整型时会抱异常                       select new AppArticleCommentModel()                       {                           Id = m.Id,                           OId = m.OId,                           MId = m.MId,                           NickName = m.NickName,                           Comment = m.Comment,                           Good = m.Good,                           Created = m.Created,                           IsHorizontal = m.IsHorizontal,                           Version = m.Version,                           From = m.From,                           ArticleName = o.Title                       };            if (!string.IsNullOrEmpty(titleName))            {                //也可在此判断添追加条件                data = data.Where(m => m.ArticleName.Contains(titleName));             }            int total = 0;            int pageSize = 10;            //对集合进行分页            var query = data.OrderByDescending(m => m.Created)                .Skip(pageSize * (pageIndex - 1)).Take(pageSize);            var list = query.ToList();            total = data.Count();            PagingHelper
      
        dataPaging = new PagingHelper
       
        (10, list);//初始化分页器            dataPaging.PageIndex = pageIndex;//指定当前页            dataPaging.PageCount = (int)Math.Ceiling(total / (double)pageSize);            dataPaging.PageSize = pageSize;            dataPaging.TotalCount = total;            return View(dataPaging);//返回分页器实例到视图        }