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上篇博客我们学习了EF CodeFirst增删改查之‘CRUD’,今儿,我们来探讨下MVC下的EF 排序、查询、分页操作
在此,本人先从分页说起
话说,做过webForm项目的程序员用AspNetPage.DLL做过分页,做过EasyUI框架的程序员,用JS AJAX请求分页,那么,MVC 程序员用什么进行分页呢?
当然,MVC程序亦可以使用上述方式进行分页
但是......
原始的分页我们要写大量的代码,或者还需要使用存储过程,在此,小弟贴一个分页的存储过程<也是一个通用的分页存储过程>,贴出这段代码的目的只有一个:让大家做一个比较。
下面,我仅仅贴出SQL端Proc的代码
GO /****** 对象: StoredProcedure [dbo].[ZXL_GetPageData] 脚本日期: 11/26/2016 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE PROCEDURE [dbo].[ZXL_GetPageData] ( @TableName varchar (500), --要进行分页的表,也可以用联接,如dbo.employee或dbo.employee INNER JOIN dbo.jobs ON (dbo.employee.job_id=dbo.jobs.job_id) @Fields varchar(3000)=‘*‘, --表中的字段,可以使用*代替 @OrderField varchar(500), --要排序的字段 @sqlWhere varchar(500)=NULL, --WHERE子句 @pageSize int, --分页的大小 @pageIndex int, --要显示的页的索引 @TotalPage int output, --页的总数 @RecordCount int output --总记录数 ) as begin Begin Tran Declare @sql nvarchar(4000); Declare @totalRecord int; --记录总数 if (@sqlWhere IS NULL or @sqlWhere = ‘‘) set @sql = ‘select @totalRecord = count(*) from ‘ + @TableName else set @sql = ‘select @totalRecord = count(*) from ‘ + @TableName + ‘ where ‘ + @sqlWhere --执行sql语句得到记录总数 EXEC sp_executesql @sql,N‘@totalRecord int OUTPUT‘,@totalRecord OUTPUT select @TotalPage=CEILING((@totalRecord+0.0)/@PageSize) select @RecordCount=CEILING(@totalRecord) --根据特定的排序字段为为行分配唯一ROW_NUMBER的顺序 if (@sqlWhere IS NULL or @sqlWhere = ‘‘) set @sql = ‘select * from (select ROW_NUMBER() over(order by ‘ + @OrderField + ‘) as rowId,‘ + @Fields + ‘ from ‘ + @TableName else set @sql = ‘select * from (select ROW_NUMBER() over(order by ‘ + @OrderField + ‘) as rowId,‘ + @Fields + ‘ from ‘ + @TableName + ‘ where ‘ + @SqlWhere --确保当前页的索引在合理的范围之内 if @PageIndex<=0 Set @pageIndex = 1 if @pageIndex>@TotalPage Set @pageIndex = @TotalPage --得到当前页在整个结果集中准确的ROW_NUMBER值 Declare @StartRecord int Declare @EndRecord int set @StartRecord = (@pageIndex-1)*@PageSize + 1 set @EndRecord = @StartRecord + @pageSize - 1 --输出当前页中的数据 set @Sql = @Sql + ‘) as t‘ + ‘ where rowId between ‘ + Convert(varchar(50),@StartRecord) + ‘ and ‘ + Convert(varchar(50),@EndRecord) Exec(@Sql) If @@Error <> 0 Begin RollBack Tran Return -1 End Else Begin Commit Tran Return @totalRecord End End
是不是一大坨?
说来惭愧,我之前写的程序都会用到这个存储过程进行分页
今天,我们换个口味,来讲述下另外一种全新的分页
首先,添加NuGet引用,搜索:pagedList
然后,在我们的Controller中添加:using PagedList;
如果我们成功添加了NuGet PagedList引用,那么,在我们的Content文件夹中就会生成一个分页的CSS文件<嘻嘻,微软不愧是世界老大哥,技术领先别人一大截,我是越来越喜欢微软了>
截止到此,准备工作也就基本做好了,下面我从后端和前端进行说明:
后端代码如下:
using System; using System.Collections.Generic; using System.Web; using System.Web.Mvc; using System.Linq; using EF_Test.DAL; using System.Data; using PagedList; namespace EF_Test.Controllers { public class HomeController : Controller { private StudentContext db = new StudentContext(); /// <summary> /// 简单分页演示 /// </summary> /// <param name="page">页码</param> /// <returns></returns> public ActionResult Index2(int page = 1)//查询所有学生数据 { return View(db.Students.OrderBy(item => item.Id).ToPagedList(page, 9)); } } }
参数Page是从前端发送的,代表页码,数字9代表每页的数量,在分页的过程中,我们必须得使用OrderBy进行排序,否则程序会出错。
前端代码如下:
@model PagedList.IPagedList<EF_Test.DAL.Student> @using PagedList.Mvc @{ ViewBag.Title = "Index"; Layout = "~/Views/Shared/_Layout.cshtml"; } @section css{ <link href="~/Content/PagedList.css" rel="stylesheet" /> <style type="text/css"> body { font-size: 12px; font-family: "微软雅黑"; color: #555; position: relative; background: #fff; } a { text-decoration: none; color: #555; } #tbList { border: 1px solid none; width: 800px; margin: 10px auto; border-collapse: collapse; } #tbList th, td { border: 1px solid #ccc; padding: 5px; text-align: center; } tfoot tr td { border: none; } </style> } @using (Html.BeginForm("Index", "Home", FormMethod.Get)) { <div style="text-align: center;"> <h1>Mvc分页例子</h1> <table id="tbList"> <tbody> @if (Model.Count() != 0) { <tr> <th>姓名 </th> <th>性别 </th> <th>学号 </th> </tr> foreach (var item in Model) { <tr style="text-align: center;"> <td> @Html.DisplayFor(modelItem => item.Name) </td> <td> @Html.DisplayFor(modelItem => item.Sex) </td> <td> @Html.DisplayFor(modelItem => item.StudentNum) </td> </tr> } } </tbody> <tfoot> <tr> <td colspan="5"> <div class=""> @if (Model != null) { <span style="height: 20px; line-height: 20px;">共 @Model.TotalItemCount.ToString() 条记录,当前第 @Model.PageNumber 页/共 @Model.PageCount 页 </span> @Html.PagedListPager(Model, page => Url.Action("Index", new { page }), new PagedListRenderOptions() { LinkToFirstPageFormat = "首页", LinkToNextPageFormat = "下一页", LinkToPreviousPageFormat = "上一页", LinkToLastPageFormat = "末页", DisplayItemSliceAndTotal = false, MaximumPageNumbersToDisplay = 3 }) } </div> </td> </tr> </tfoot> </table> </div> }
前端没什么好说的,大家自己测试,运行结果如下
至此,MVC分页也就讲完了,下面我们来探讨排序的查询的问题
好吧,由于小弟还没吃饭,就不作说明了,直接上代码:
前端变更如下:
@model PagedList.IPagedList<EF_Test.DAL.Student> @using PagedList.Mvc @{ ViewBag.Title = "Index"; Layout = "~/Views/Shared/_Layout.cshtml"; } @section css{ <link href="~/Content/PagedList.css" rel="stylesheet" /> <style type="text/css"> body { font-size: 12px; font-family: "微软雅黑"; color: #555; position: relative; background: #fff; } a { text-decoration: none; color: #555; } #tbList { border: 1px solid none; width: 800px; margin: 10px auto; border-collapse: collapse; } #tbList th, td { border: 1px solid #ccc; padding: 5px; text-align: center; } tfoot tr td { border: none; } </style> } @using (Html.BeginForm("Index", "Home", FormMethod.Get)) { <div style="text-align: center;"> <h1>Mvc分页例子</h1> <table id="tbList"> <tbody> @if (Model.Count() != 0) { <tr> <th>姓名 </th> <th>性别 </th> <th>学号 </th> </tr> foreach (var item in Model) { <tr style="text-align: center;"> <td> @Html.DisplayFor(modelItem => item.Name) </td> <td> @Html.DisplayFor(modelItem => item.Sex) </td> <td> @Html.DisplayFor(modelItem => item.StudentNum) </td> </tr> } } </tbody> <tfoot> <tr> <td colspan="5"> <div class=""> @if (Model != null) { <span style="height: 20px; line-height: 20px;">共 @Model.TotalItemCount.ToString() 条记录,当前第 @Model.PageNumber 页/共 @Model.PageCount 页 </span> @Html.PagedListPager(Model, page => Url.Action("Index", new { page }), new PagedListRenderOptions() { LinkToFirstPageFormat = "首页", LinkToNextPageFormat = "下一页", LinkToPreviousPageFormat = "上一页", LinkToLastPageFormat = "末页", DisplayItemSliceAndTotal = false, MaximumPageNumbersToDisplay = 3 }) } </div> </td> </tr> </tfoot> </table> </div> }
说明几点:
查询使用的是表单Get请求、
多加了两个文本框和一个sumbit按钮,用作查询
姓名和学号做成<A>标签,用作排序,例如:点击姓名,按照姓名升序排,再次点击,按照姓名降序排,同理点击学号
后端代码如下:
/// <summary> /// 查询 排序 分页 /// </summary> /// <param name="sortOrder">排序字段 默认Id desc</param> /// <param name="stuName">搜索框 学生姓名 模糊查询</param> /// <param name="stuNum">搜索框 学生学号 精确查询</param> /// <param name="page">页码</param> /// <returns></returns> public ActionResult Index(string sortOrder, string stuName, string stuNum, int page = 1)//查询所有学生数据 { //初始化排序-默认排序 ViewBag.NameSortParm = "NameAsc"; ViewBag.StumSortParm = "StumAsc"; //根据click 更改排序 if (!string.IsNullOrEmpty(sortOrder)) { if (sortOrder.Contains("Name")) { if (sortOrder.Equals("NameAsc")) { sortOrder = "NameDesc"; ViewBag.NameSortParm = sortOrder; } else { sortOrder = "NameAsc"; ViewBag.NameSortParm = sortOrder; } } if (sortOrder.Contains("Stum")) { if (sortOrder.Equals("StumAsc")) { sortOrder = "StumDesc"; ViewBag.StumSortParm = sortOrder; } else { sortOrder = "StumAsc"; ViewBag.StumSortParm = sortOrder; } } } //} //查询全部数据 var students = from s in db.Students select s; //根据查询条件检索 if (!string.IsNullOrEmpty(stuName)) { //根据姓名模糊查询 students = students.Where(s => s.Name.Contains(stuName)); } if (!string.IsNullOrEmpty(stuNum)) { //根据学号精确查询 students = students.Where(s => s.StudentNum==stuName); } //排序处理 switch (sortOrder) { case "NameDesc": students = students.OrderByDescending(item=>item.Name); break; case "NameAsc": students = students.OrderBy(item => item.Name); break; case "StumAsc": students = students.OrderBy(s => s.StudentNum); break; case "StumDesc": students = students.OrderByDescending(s => s.StudentNum); break; default: students = students.OrderByDescending(s => s.Id); break; } return View(students.ToPagedList(page, 9));// }
运行结果:
默认排序:ID 倒序排列
点击姓名,按照姓名倒序排列,如下:
再次点击姓名,按照姓名升序排列、
同理,点击学号,不做演示
输入姓名,进行模糊查询
同理,输入学号进行精确查询,不做演示!
吃饭喽,
@陈卧龙的博客