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。
演练5-2：Contoso大学校园管理2

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。

演练5-2：Contoso大学校园管理2

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。

演练5-2：Contoso大学校园管理2

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 = 1;
 }
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 = 3;
int pageNumber = (page ?? 1);
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 ? 0 : 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。

演练5-2：Contoso大学校园管理2

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>

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演练5-2：Contoso大学校园管理2

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