EF 利用PagedList进行分页并结合查询 方法2

微软提供了PagedList分页，相信大家在网上也能搜索一大堆关于pagedList用法的博客，论坛。但是，在使用的过程中一不小心，就会掉入pagedList某种常规用法的陷阱。

我所说的某种常规用法是指如下方法(也可以参考我的博客：PagedList 分页用法)：

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 = )//查询所有学生数据
        {
            return View(db.Students.OrderBy(item => item.Id).ToPagedList(page, ));
        }
    }
}

前端HTML

@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>
}

上述的用法很简单，直接查询所有数据，然后利用pagedList提供的HTML helper 进行分页。

其效果图也不错，如下：

上述中红色字体提到：该用法需要一次性查询表中所有数据，试问：如果您的数据表中有百万甚至千万条数据，那么这种用法效率是不是将会很低？

说来也惭愧，当初用的时候，我也想到了这个弊端，但是一直没去想办法解决这个问题。

还好，pagedList还提供了另外一种方法：StaticPagedList 方法

StaticPagedList 方法需要提供四个参数，分别为：数据源  当前页码  每页条数  以及总记录数

如上述所言，我们在查询的过程中不能一次性查询所有数据，因为这样做效率很低。而现在我们要做的就是查询当前页码的 10 条数据(假设每页展示十条数据)及返回数据表中的总记录数。

那么我们该怎么做呢？

方法其实很多，在我的项目中，我用到一个存储过程<不管你用什么，你现在要做的就是返回：当前页码的 10 条数据，及数据表总记录条数>

我用到的存储过程为：请参考我的上篇博客

有了存储过程，我们就要用EF执行这个存储过程，怎么执行呢？

接口层：

IEnumerable<StudentModel> GetPagePro(string tableName, string fields, string orderField, string sqlWhere, int pageSize, int pageIndex, out int totalPage, out int RecordCount);

执行层：继承接口

        /// <summary>
        /// EF执行存储过程
        /// </summary>
        /// <param name="tableName">表名</param>
        /// <param name="fields">所要查询的字段</param>
        /// <param name="orderField">排序字段</param>
        /// <param name="sqlWhere">条件语句 where</param>
        /// <param name="pageSize">页容量</param>
        /// <param name="pageIndex">页码</param>
        /// <param name="totalPage">out参数 总分页数量</param>
        /// <param name="RecordCount">out 参数 总记录数</param>
        /// <returns></returns>
        public IEnumerable<StudentModel> GetPagePro(string tableName, string fields, string orderField, string sqlWhere, int pageSize, int pageIndex, out int totalPage, out int RecordCount)
         {
            using (StudentEntities context = new StudentEntities())
            {
                SqlParameter[] parameters = {
                    new SqlParameter("@TableName", SqlDbType.NText),
                    new SqlParameter("@Fields", SqlDbType.NText),
                    new SqlParameter("@OrderField", SqlDbType.NText),
                    new SqlParameter("@sqlWhere", SqlDbType.NText),
                    new SqlParameter("@pageSize", SqlDbType.Int),
                    new SqlParameter("@pageIndex", SqlDbType.Int),
                    new SqlParameter("@TotalPage", SqlDbType.Int),
                    new SqlParameter("@RecordCount", SqlDbType.Int)
                    };
                parameters[].Value = tableName;
                parameters[].Value = fields;
                parameters[].Value = orderField;
                parameters[].Value = sqlWhere;
                parameters[].Value = pageSize;
                parameters[].Value = pageIndex;
                parameters[].Direction = ParameterDirection.Output;
                parameters[].Direction = ParameterDirection.Output;
                var data = context.Database.SqlQuery<StudentModel>("exec [ZXL_GetPageData] @TableName,@Fields,@OrderField,@sqlWhere,@pageSize,@pageIndex,@TotalPage out,@RecordCount out", parameters).ToList();
                int count = data.Count;
                //
                string n6 = parameters[].Value.ToString();
                string n7 = parameters[].Value.ToString();
                //
                totalPage = !string.IsNullOrEmpty(n6) ? int.Parse(n6) : ;
                RecordCount = !string.IsNullOrEmpty(n7) ? int.Parse(n7) : ;
                return data;
            }
        }

实体Model层：

    public class StudentModel
    {
        public int Id { get; set; }
        public string StuNum { get; set; }
        public string deptNum { get; set; }
        public string StuName { get; set; }
        public string StuSex { get; set; }
        public Nullable<System.DateTime> AddTime { get; set; }
    }

控制器代码：

        public ActionResult Index(int page=)//查询所有学生数据
        {
            int totalPage=;
            int recordCount=;
            var  data = studentdb.GetPagePro("Student", "*", "Id", "", , page, out totalPage, out recordCount);
            var studentList = new StaticPagedList<StudentModel>(data,page,,recordCount);
            return View(studentList);//
        }

UI/View层

@model PagedList.StaticPagedList<Test.Model.StudentModel>
@using PagedList.Mvc
@using PagedList
@{
    ViewBag.Title = "Index";
    Layout = null;
}
<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">
           @* <thead>
                <tr>
                    <th>
                        <input id="StuName" name="StuName" type="text" placeholder="请输入姓名" />
                    </th>
                    <th>
                        <input id="StuNum" name="StuNum" type="text" placeholder="请输入学号" />
                    </th>
                    <th>
                        <input id="Submit1" type="submit" value="submit" />
                    </th>
                </tr>
            </thead>*@

            <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.StuName)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.StuSex)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.StuNum)
                        </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>
}

上述代码已经很齐全了，大家可以自行尝试，需要说明两点：

控制器代码：

view层HTML代码：

至此，整个pagedList分页就完毕了。

这样查询提升了效率。

我的分页效果图如下：

由图可知，我的数据表共有：151303条记录，如果采用每次都加载所有数据，效率是何其低可想而知。

呵呵，截止到这儿，pagedlist分页也就讲完了！

现在，我们提出新的要求：结合查询，根据学生姓名和学号进行模糊查询

其后端变更如下：

        public ActionResult Index(int page = , string StuName = "", string StuNum = "",string sortOrder="")//查询所有学生数据
        {
            string where = string.Empty;
            if (!string.IsNullOrEmpty(StuName))
            {
                ViewBag.StuName = StuName;
                where += " and StuName like '%" + StuName + "%'";
            }
            if (!string.IsNullOrEmpty(StuNum))
            {
                ViewBag.StuNum = StuNum;
                where += " and StuNum like '%" + StuNum + "%'";
            }
            int totalPage = ;
            int recordCount = ;
            var data = model.GetPagePro("Student", "*", "Id", " 1=1 " + where, , page, out totalPage, out recordCount);

            var studentList = new StaticPagedList<StudentModel>(data, page, , recordCount);
            return View(studentList);//
        }

前端如下：

@model PagedList.StaticPagedList<Test.Model.StudentModel>
@using PagedList.Mvc
@using PagedList
@{
    ViewBag.Title = "Index";
    Layout = null;
}
<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">
            <thead>
                <tr>
                    <th>
                        <input id="StuName" name="StuName" type="text" placeholder="请输入姓名" value="@ViewBag.StuName" />
                    </th>
                    <th>
                        <input id="StuNum" name="StuNum" type="text" placeholder="请输入学号" value="@ViewBag.StuNum" />
                    </th>
                    <th>
                        <input id="Submit1" type="submit" value="submit" />
                    </th>
                </tr>
            </thead>

            <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.StuName)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.StuSex)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.StuNum)
                        </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,StuName=ViewBag.StuName,StuNum=ViewBag.StuNum }), 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>
}

上图为变更处、

运行效果：

@陈卧龙的博客