演练5-2：Contoso大学校园管理2

一、添加列标题排序功能

我们将增加Student/Index页面的功能，为列标题添加超链接，用户可以点击列标题对那一列进行排序。

1.修改Index方法

public ActionResult Index(string sortOrder)

{

   ViewBag.NameSortParm = String.IsNullOrEmpty(sortOrder) ? "Name_desc" : "";

   ViewBag.DateSortParm = sortOrder == "Date" ? "Date_desc" : "Date";

   var students = from s in db.Students

                  select s;

   switch (sortOrder)

   {

      case "Name_desc":

         students = students.OrderByDescending(s => s.LastName);

         break;

      case "Date":

         students = students.OrderBy(s => s.EnrollmentDate);

         break;

      case "Date_desc":

         students = students.OrderByDescending(s => s.EnrollmentDate);

         break;

      default:

         students = students.OrderBy(s => s.LastName);

         break;

   }

   return View(students.ToList());

}

第一次Index页面响应的时候，没有query string，学生按照LastName升序排序，这是?:表达式的默认值，switch 语句执行升序操作。当用户点击列标题的超链接，正确的sortOrder参数传给query string。

两个ViewBag变量用来区分列标题的超链接，是选择哪一个query string。

2.在Student\Index视图中，添加列标题超链接

<p>

    @Html.ActionLink("Create New", "Create")

</p>

<table>

    <tr>

        <th>

            @Html.ActionLink("Last Name", "Index", new { sortOrder = ViewBag.NameSortParm })

        </th>

        <th>First Name

        </th>

        <th>

            @Html.ActionLink("Enrollment Date", "Index", new { sortOrder = ViewBag.DateSortParm })

        </th>

        <th></th>

    </tr>

    @foreach (var item in Model)

    {

运行验证效果。

二、添加一个搜索文本框

添加一个按照first name、last name搜索的文本框，实现对数据的过滤。

1.Index方法中添加过滤功能

public ViewResult Index(string sortOrder, string searchString)

{

    ViewBag.NameSortParm = String.IsNullOrEmpty(sortOrder) ? "name_desc" : "";

    ViewBag.DateSortParm = sortOrder == "Date" ? "date_desc" : "Date";

    var students = from s in db.Students

                   select s;

    if (!String.IsNullOrEmpty(searchString))

    {

        students = students.Where(s => s.LastName.ToUpper().Contains(searchString.ToUpper())

                               || s.FirstMidName.ToUpper().Contains(searchString.ToUpper()));

    }

    switch (sortOrder)

    {

        case "name_desc":

            students = students.OrderByDescending(s => s.LastName);

            break;

        case "Date":

            students = students.OrderBy(s => s.EnrollmentDate);

            break;

        case "date_desc":

            students = students.OrderByDescending(s => s.EnrollmentDate);

            break;

        default:

            students = students.OrderBy(s => s.LastName);

            break;

    }

    return View(students.ToList());

}

2.在Index视图中添加Search文本框

<p>

    @Html.ActionLink("Create New", "Create")

</p>

@using (Html.BeginForm())

{

    <p>

        Find by name: @Html.TextBox("SearchString")

        <input type="submit" value="Search" /></p>

}

<table>

    <tr>

运行查看效果。

细心的同学有没有发现神马问题？搜索和排序功能同时能用么？

 三、添加分页功能

我们将使用PagedList.Mvc NuGet包，实现分页功能。

1.安装PagedList.MVC NuGet Package

PagedList包安装了一个PagedList集合类型，并且扩展方法适用于IQueryable和IEnumerable集合。

2.为Index方法添加分页功能

using PagedList;

public ViewResult Index(string sortOrder, string currentFilter, string searchString, int? page)

{

   ViewBag.CurrentSort = sortOrder;

   ViewBag.NameSortParm = String.IsNullOrEmpty(sortOrder) ? "name_desc" : "";

   ViewBag.DateSortParm = sortOrder == "Date" ? "date_desc" : "Date";

   if (searchString != null)

   {

      page = ;

   }

  else

   {

      searchString = currentFilter;

   }

   ViewBag.CurrentFilter = searchString;

   var students = from s in db.Students

                  select s;

   if (!String.IsNullOrEmpty(searchString))

   {

      students = students.Where(s => s.LastName.ToUpper().Contains(searchString.ToUpper())

                             || s.FirstMidName.ToUpper().Contains(searchString.ToUpper()));

   }

   switch (sortOrder)

   {

      case "name_desc":

         students = students.OrderByDescending(s => s.LastName);

         break;

      case "Date":

         students = students.OrderBy(s => s.EnrollmentDate);

         break;

      case "date_desc":

         students = students.OrderByDescending(s => s.EnrollmentDate);

         break;

      default:  // Name ascending

         students = students.OrderBy(s => s.LastName);

         break;

   }

   int pageSize = ;

   int pageNumber = (page ?? );

   return View(students.ToPagedList(pageNumber, pageSize));

}

3.在Student\Index视图，添加页码链接

@model PagedList.IPagedList<ContosoUniversity.Models.Student>

@using PagedList.Mvc;

<link href="~/Content/PagedList.css" rel="stylesheet" type="text/css" />

@{

    ViewBag.Title = "Students";

}

<h2>Students</h2>

<p>

    @Html.ActionLink("Create New", "Create")

</p>

@using (Html.BeginForm("Index", "Student", FormMethod.Get))

{

    <p>

        Find by name: @Html.TextBox("SearchString", ViewBag.CurrentFilter as string)

        <input type="submit" value="Search" />

    </p>

}

<table>

<tr>

    <th></th>

    <th>

        @Html.ActionLink("Last Name", "Index", new { sortOrder=ViewBag.NameSortParm, currentFilter=ViewBag.CurrentFilter })

    </th>

    <th>

        First Name

    </th>

    <th>

        @Html.ActionLink("Enrollment Date", "Index", new { sortOrder = ViewBag.DateSortParm, currentFilter = ViewBag.CurrentFilter })

    </th>

</tr>

@foreach (var item in Model) {

    <tr>

        <td>

            @Html.ActionLink("Edit", "Edit", new { id=item.StudentID }) |

            @Html.ActionLink("Details", "Details", new { id=item.StudentID }) |

            @Html.ActionLink("Delete", "Delete", new { id=item.StudentID })

        </td>

        <td>

            @Html.DisplayFor(modelItem => item.LastName)

        </td>

        <td>

            @Html.DisplayFor(modelItem => item.FirstMidName)

        </td>

        <td>

            @Html.DisplayFor(modelItem => item.EnrollmentDate)

        </td>

    </tr>

}

</table>

<br />

Page @(Model.PageCount < Model.PageNumber ?  : Model.PageNumber) of @Model.PageCount

@Html.PagedListPager( Model, page => Url.Action("Index", new { page, sortOrder = ViewBag.CurrentSort, currentFilter=ViewBag.CurrentFilter }) )

你可以使用PagedListPager帮助器定制自己的分页效果，包括URLs和样式，查看更多信息请点击TroyGoode  / PagedList on the GitHub site。

@Html.TextBox("SearchString", ViewBag.CurrentFilter as string)  中，ViewBag的值绑定都SearchString文本框上。

四、创建学生数据分析页面

在About页面中，我们将显示每天有多少学生注册。

1.创建视图模型

using System;

using System.ComponentModel.DataAnnotations;

namespace ContosoUniversity.ViewModels

{

    public class EnrollmentDateGroup

    {

        [DataType(DataType.Date)]

        public DateTime? EnrollmentDate { get; set; }

        public int StudentCount { get; set; }

    }

}

2.修改Home控制器

using ContosoUniversity.DAL;

using ContosoUniversity.ViewModels;

public class HomeController : Controller

    {

        private SchoolContext db = new SchoolContext();

public ActionResult About()

{

    var data = from student in db.Students

               group student by student.EnrollmentDate into dateGroup

               select new EnrollmentDateGroup()

               {

                   EnrollmentDate = dateGroup.Key,

                   StudentCount = dateGroup.Count()

               };

    return View(data);

}

protected override void Dispose(bool disposing)

{

    db.Dispose();

    base.Dispose(disposing);

}

3.修改About视图

@model IEnumerable<ContosoUniversity.ViewModels.EnrollmentDateGroup>

@{

    ViewBag.Title = "Student Body Statistics";

}

<h2>Student Body Statistics</h2>

<table>

    <tr>

        <th>

            Enrollment Date

        </th>

        <th>

            Students

        </th>

    </tr>

@foreach (var item in Model) {

    <tr>

        <td>

            @Html.DisplayFor(modelItem => item.EnrollmentDate)

        </td>

        <td>

            @item.StudentCount

        </td>

    </tr>

}

</table>