MVC – 4.mvc初体验(2)

5.显示学员列表

效果

数据表

5.1 首先，在文件夹Models新建一个新建项（W）,选择ADO.NET 实体数据模型 (SingleTest.edmx)

5.2 建一个控制器，StudentsController.cs

StudentsController.cs

StudentsController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace P01FirstMVC.Controllers
{
    public class StudentsController : Controller
    {
        //创建数据上下文
        Models.SingleTestEntities db = new Models.SingleTestEntities();

        /// <summary>
        /// 显示学院列表
        /// </summary>
        /// <returns></returns>
        public ActionResult Index()
        {
            //1.查询学员数据（EF查询到实体其实是 实体代理类对象（包装类对象））
            List<Models.Student> list = (from s in db.Students.Include("class") where s.Isdel == 1 select s).ToList();
            //2.加载视图，并将数据传给视图
            return View(list);
        }

    }
}

5.3 再生成一个视图

Views\Students\Index.cshtml

Views\Students\Index.cshtml

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
    <style>
        #tbList{
            border:1px solid #0094ff;
            width:400px;
            margin:20px auto;
            border-collapse:collapse;
        }
            #tbList th, td {
                border: 1px solid #0094ff;
                padding:2px;
            }
    </style>
</head>
<body>
    <div>
        <table id="tbList">
            <tbody>
                <tr>
                    <th>ID</th>
                    <th>姓名</th>
                    <th>班级</th>
                    <th>性别</th>
                </tr>
                <!--视图包含一个 Model属性 可以通过控制器 Action 方法里的 View(modeldata)赋值-->
                @foreach (P01FirstMVC.Models.Student stu in Model as List<P01FirstMVC.Models.Student>)
                {
                    <tr>
                    <th>@stu.StudentID</th>
                    <th>@stu.Name</th>
                    <th>@stu.Class.CName</th>
                    <th>@stu.Gender</th>
                </tr>
                }
            </tbody>
        </table>
    </div>
</body>
</html>

6.删除

6.1.修改上图

@foreach (P01FirstMVC.Models.Student stu in Model as List<P01FirstMVC.Models.Student>)
                {
                    <tr>
                        <th>@stu.StudentID</th>
                        <th>@stu.Name</th>
                        <th>@stu.Class.CName</th>
                        <th>@stu.Gender</th>
                        <th><a href="/students/del/@stu.StudentID">删</a></th>
                    </tr>
                }

6.2.然后再在控制器添加删除方法Del()

StudentsController.cs 2.0 删除

StudentsController.cs 2.0 删除

        #region 2.0 删除 指定学员数据
        /// <summary>
        /// 删除 指定学员数据
        /// </summary>
        /// <returns></returns>
        public void Del(int id)
        {
            //2.1 检查id是否存在
            //2.2 执行删除
            Models.Student stu = new Models.Student() { StudentID = id };

            /*等价于下面的entry方法
            db.Students.Attach(stu);
            db.Students.Remove(stu);
            */
            DbEntityEntry<Models.Student> entry = db.Entry<Models.Student>(stu);
            entry.State = EntityState.Deleted;

            int reslut = db.SaveChanges();
            //return JavaScript("alert('删除成功！');window.location='/Students/Index';");
            //return Redirect("/Students/Index");//重定向方法，相当于Response.Redirect("/Students/Index");
            Response.Write("<script>alert('删除成功！');window.location='/Students/Index';</script>");
        }
        #endregion

7.修改

\Views\Students\Modify.cshtml

\Views\Students\Modify.cshtml

@{
    Layout = null;
}
@using P01FirstMVC.Models;
@model P01FirstMVC.Models.Student
<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Modify</title>
</head>
<body>
    <div>
        <form action="/Students/Modify" method="post">
            <input type="hidden" name="StudentID" value="@Model.StudentID" />
            <table>
                <tbody>
                    <tr>
                        <td>姓名:</td>
                        <td><input name="Name" value="@Model.Name" /></td>
                    </tr>
                    <tr>
                        <td>班级:</td>
                        <td>
                            @*方法二*@
@Html.DropDownList("Cid", ViewBag.classes as IEnumerable<SelectListItem>)

                            @*方法一：查询班级下拉列表
                                    <select name="Cid">
                                   @foreach (Class item in @ViewBag.classes as List<Class>)
                                   {
                                       //表classes的cid与表student表的cid相等
                                       if (item.Cid==Model.Cid)
                                       {
                                           <option selected value="@item.Cid">@item.CName</option>
                                       }
                                       else
                                       {
                                           <option value="@item.Cid">@item.CName</option>
                                       }

                                   }
                                </select>*@
</td>
                    </tr>
                </tbody>
            </table>
            <input type="submit" value="OK" />
        </form>
    </div>
</body>
</html>

StudentsController.cs 3.0 修改

StudentsController.cs 3.0 修改

 #region 3.0 修改
        /// <summary>
        /// 修改
        /// </summary>
        /// <returns></returns>
        public ActionResult Modify(int id)
        {
            //3.1.检查id是否存在

            //3.2.根据id查询数据
            Models.Student stu = (from s in db.Students where s.Isdel == 1 && s.StudentID == id select s).FirstOrDefault();

            //3.3.方法一：查询班级下拉列表
            //List<Models.Class> classes = (from p in db.Classes where p.CIsdel == "0" select p).ToList();
            //ViewBag.classes = classes;

            //3.3.方法二：查询班级数据并转成下拉框选项 集合
            //**************linq查询不识别方法“System.String ToString(Int32)”，因此该方法无法转换为存储表达式。
            //*List<SelectListItem> selectClasses = (from p in db.Classes
            //*                                      where p.CIsdel == "0"
            //*                                      select new SelectListItem()
            //*                                      {
            //*                                          Text = p.CName,
            //*                                          Value = p.Cid.ToString(),
            //*                                          Selected = (stu.Cid == p.Cid)
            //*                                      }).ToList();
            //******************************************************************************
            List<SelectListItem> cals = db.Classes.Where(p => p.CIsdel == "0").ToList() //选查询数据转成 实体List集合
                .Select(p => new SelectListItem()
                                 {
                                     Text = p.CName,
                                     Value = p.Cid.ToString(),   //先转成List集合，才能使用ToString()
                                     Selected = (stu.Cid == p.Cid)
                                 }).ToList();                                           //将实体集合转成SelectListItem集合
            ViewBag.classes = cals;

            //3.4.加载视图 并传递要修改的值
            return View(stu);

        }

        //[HttpPost]
        [HttpPost]
        public ActionResult Modify(Models.Student model)
        {
            DbEntityEntry entry = db.Entry<Models.Student>(model);
            entry.State = EntityState.Unchanged;
            entry.Property("Name").IsModified = true;
            entry.Property("Cid").IsModified = true;
            db.SaveChanges();
            return Redirect("/Students/index");
        }
        #endregion