Linq 數據排序，分頁

  在用Linq查詢中，常常需要用到分頁功能，因為每次都需要些分頁這些功能，於是把分頁功能提取出來，不喜大家勿噴，只是貼出來，自覺地很實用。一下貼出核心代碼：

 1  /// <summary>
 2     /// LinqHelper 主要用於數據集，排序 分頁等功能
 3     /// </summary>
 4     public class LinqHelper
 5     {
 6         /// <summary>
 7         /// 排序
 8         /// </summary>
 9         /// <typeparam name="T"></typeparam>
10         /// <param name="source"></param>
11         /// <param name="sortExpression"></param>
12         /// <param name="sortDirection"></param>
13         /// <returns></returns>
14         public static IQueryable<T> DataSorting<T>(IQueryable<T> source, string sortExpression, string sortDirection)
15         {
16             string sortingDir = string.Empty;
17             if (sortDirection.ToUpper().Trim() == "ASC")
18                 sortingDir = "OrderBy";
19             else if (sortDirection.ToUpper().Trim() == "DESC")
20                 sortingDir = "OrderByDescending";
21             ParameterExpression param = Expression.Parameter(typeof(T), sortExpression);
22             PropertyInfo pi = typeof(T).GetProperty(sortExpression);
23             Type[] types = new Type[2];
24             types[0] = typeof(T);
25             types[1] = pi.PropertyType;
26             Expression expr = Expression.Call(typeof(Queryable), sortingDir, types, source.Expression, Expression.Lambda(Expression.Property(param, sortExpression), param));
27             IQueryable<T> query = source.AsQueryable().Provider.CreateQuery<T>(expr);
28             return query;
29         }
30         /// <summary>
31         /// 分頁
32         /// </summary>
33         /// <typeparam name="T"></typeparam>
34         /// <param name="source"></param>
35         /// <param name="pageNumber"></param>
36         /// <param name="pageSize"></param>
37         /// <returns></returns>
38         public static IQueryable<T> DataPaging<T>(IQueryable<T> source, int pageNumber, int pageSize)
39         {
40             return source.Skip((pageNumber - 1) * pageSize).Take(pageSize);
41         }
42         /// <summary>
43         /// 排序並分頁 
44         /// </summary>
45         /// <typeparam name="T"></typeparam>
46         /// <param name="source"></param>
47         /// <param name="sortExpression"></param>
48         /// <param name="sortDirection"></param>
49         /// <param name="pageNumber"></param>
50         /// <param name="pageSize"></param>
51         /// <returns></returns>
52         public static IQueryable<T> SortingAndPaging<T>(IQueryable<T> source, string sortExpression, string sortDirection, int pageNumber, int pageSize)
53         {
54             if (!string.IsNullOrEmpty(sortDirection))
55             {
56                 //  IQueryable<T> query = DataSorting<T>(source, sortExpression, sortDirection);
57             }
58             IQueryable<T> query = source.AsQueryable();
59             return DataPaging(query, pageNumber, pageSize);
60         }
61     }

在分頁中需要一個輔助的類用於分頁排序的類，用於限定分頁的參數：

 1 //排序用到的參數
 2     public class GridPager
 3     {
 4         /// <summary>
 5         /// //每頁行數
 6         /// </summary>
 7         public int rows { get; set; }
 8         /// <summary>
 9         /// //當前頁是第幾頁
10         /// </summary>
11         public int page { get; set; }
12         /// <summary>
13         /// //排序方式
14         /// </summary>
15         public string order { get; set; }
16         /// <summary>
17         /// //排序列
18         /// </summary>
19         public string sort { get; set; }
20         /// <summary>
21         /// //總行數 
22         /// </summary>
23         public int totalRows { get; set; }     
24     }

 使用方法*.ASP中 XXXX.ashx一般處理程式中，調用方法為：

 1  public void GetAllInfoRW(HttpContext context)
 2     {
 3         string retStr = "";
 4         string rowsStr = "";
 5         int rCount = 0;
 6        GridPager pager = new GridPager
 7         {
 8             page = Convert.ToInt32(context.Request["page"]),
 9             rows = Convert.ToInt32(context.Request["rows"]),
10             sort = "RTime",
11             order = "DESC"
12         };
13         string chk = context.Request["chk"].ToString();
14         List<ShowCCK_DHModle> list = CCRK_CKDBiz.GetAllShowInfo(chk,ref rCount);
15         var resout = LinqHelper.SortingAndPaging(list.AsQueryable(), pager.sort, pager.sort, pager.page, pager.rows);
16         rowsStr = JsonConvert.SerializeObject(list);
17 
18         retStr = "{\"total\":\"" + rCount + "\",\"rows\":" + rowsStr + "}";
19 
20         context.Response.Write(retStr);
21     }

在easyui-datagrid中註意json格式

在使用JsonConvert.SerializeObject(object); 方法中需要引入命名空間，【using  Newtonsoft.Json】可以通過可以通過Nuget程式管理工具在http://www.nuget.org/官網上下載

在VS中通過Nuget程式管理工具輸入命令：Install-Package Newtonsoft.Json