Linq 数据排序，分页

  在用Linq查询中，常常需要用到分页功能，因为每次都需要些分页这些功能，于是把分页功能提取出来，不喜大家勿喷，只是贴出来，自觉地很实用。一下贴出核心代码：

 /// <summary>
    /// LinqHelper 主要用于数据集，排序 分页等功能
    /// </summary>
    public class LinqHelper
    {
        /// <summary>
        /// 排序
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="source"></param>
        /// <param name="sortExpression"></param>
        /// <param name="sortDirection"></param>
        /// <returns></returns>
        public static IQueryable<T> DataSorting<T>(IQueryable<T> source, string sortExpression, string sortDirection)
        {
            string sortingDir = string.Empty;
            if (sortDirection.ToUpper().Trim() == "ASC")
                sortingDir = "OrderBy";
            else if (sortDirection.ToUpper().Trim() == "DESC")
                sortingDir = "OrderByDescending";
            ParameterExpression param = Expression.Parameter(typeof(T), sortExpression);
            PropertyInfo pi = typeof(T).GetProperty(sortExpression);
            Type[] types = new Type[2];
            types[0] = typeof(T);
            types[1] = pi.PropertyType;
            Expression expr = Expression.Call(typeof(Queryable), sortingDir, types, source.Expression, Expression.Lambda(Expression.Property(param, sortExpression), param));
            IQueryable<T> query = source.AsQueryable().Provider.CreateQuery<T>(expr);
            return query;
        }
        /// <summary>
        /// 分页
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="source"></param>
        /// <param name="pageNumber"></param>
        /// <param name="pageSize"></param>
        /// <returns></returns>
        public static IQueryable<T> DataPaging<T>(IQueryable<T> source, int pageNumber, int pageSize)
        {
            return source.Skip((pageNumber - 1) * pageSize).Take(pageSize);
        }
        /// <summary>
        /// 排序并分页 
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="source"></param>
        /// <param name="sortExpression"></param>
        /// <param name="sortDirection"></param>
        /// <param name="pageNumber"></param>
        /// <param name="pageSize"></param>
        /// <returns></returns>
        public static IQueryable<T> SortingAndPaging<T>(IQueryable<T> source, string sortExpression, string sortDirection, int pageNumber, int pageSize)
        {
            if (!string.IsNullOrEmpty(sortDirection))
            {
                //  IQueryable<T> query = DataSorting<T>(source, sortExpression, sortDirection);
            }
            IQueryable<T> query = source.AsQueryable();
            return DataPaging(query, pageNumber, pageSize);
        }
    }

在分页中需要一个辅助的类用于分页排序的类，用于限定分页的参数：

//排序用到的参数
    public class GridPager
    {
        /// <summary>
        /// //每页行数
        /// </summary>
        public int rows { get; set; }
        /// <summary>
        /// //当前页是第几页
        /// </summary>
        public int page { get; set; }
        /// <summary>
        /// //排序方式
        /// </summary>
        public string order { get; set; }
        /// <summary>
        /// //排序列
        /// </summary>
        public string sort { get; set; }
        /// <summary>
        /// //总行数 
        /// </summary>
        public int totalRows { get; set; }     
    }

 使用方法*.ASP中 XXXX.ashx一般处理程序中，调用方法为：

 public void GetAllInfoRW(HttpContext context)
    {
        string retStr = "";
        string rowsStr = "";
        int rCount = 0;
       GridPager pager = new GridPager
        {
            page = Convert.ToInt32(context.Request["page"]),
            rows = Convert.ToInt32(context.Request["rows"]),
            sort = "RTime",
            order = "DESC"
        };
        string chk = context.Request["chk"].ToString();
        List<ShowCCK_DHModle> list = CCRK_CKDBiz.GetAllShowInfo(chk,ref rCount);
        var resout = LinqHelper.SortingAndPaging(list.AsQueryable(), pager.sort, pager.sort, pager.page, pager.rows);
        rowsStr = JsonConvert.SerializeObject(list);

        retStr = "{"total":"" + rCount + "","rows":" + rowsStr + "}";

        context.Response.Write(retStr);
    }

在easyui-datagrid中注意json格式

在使用JsonConvert.SerializeObject(object); 方法中需要引入命名空间，【using  Newtonsoft.Json】可以通过可以通过Nuget程序管理工具在http://www.nuget.org/官网上下载

在VS中通过Nuget程序管理工具输入命令：Install-Package Newtonsoft.Json