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[];
             types[] = typeof(T);
             types[] = 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 - ) * 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 = ;
        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