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