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📜  使用C＃和实体框架的ASP.NET MVC中的基本CRUD(创建，读取，更新，删除)(1)

📅  最后修改于: 2023-12-03 15:36:35.505000             🧑  作者: Mango

使用C#和实体框架的ASP.NET MVC中的基本CRUD

在ASP.NET MVC应用程序中，CRUD操作（创建，读取，更新，删除）是常见的任务。这些操作允许应用程序的用户管理其数据。这里将介绍如何使用C＃和实体框架来实现基本的CRUD操作。

准备工作

  1. 首先要创建一个ASP.NET MVC应用程序。

  2. 在Visual Studio中，打开“解决方案资源管理器”，右键点击解决方案，选择“管理NuGet程序包”选项，搜索并安装以下依赖项：

    • EntityFramework
    • Microsoft.AspNet.Mvc
    • Microsoft.AspNet.WebApi.Core

  3. 在web.config文件中，添加以下连接字符串：

    <connectionStrings>
  <add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=MyDatabase;Integrated Security=SSPI;" providerName="System.Data.SqlClient" />
</connectionStrings>

    修改Data Source、Initial Catalog和Integrated Security选项以连接到您的数据库。

创建模型

  1. 在Models文件夹中，添加一个名为TodoItem.cs的新类。

  2. 添加以下代码：

    using System.ComponentModel.DataAnnotations;

public class TodoItem
{
    public int Id { get; set; }

    [Required]
    public string Title { get; set; }

    public string Description { get; set; }

    [Display(Name = "Due Date")]
    [DataType(DataType.DateTime)]
    public DateTime DueDate { get; set; }
}

    此模型表示一个待办事项。

创建控制器

  1. 在Controllers文件夹中，添加一个名为TodoController.cs的新类。

  2. 添加以下代码：

    using System;
using System.Data.Entity;
using System.Linq;
using System.Net;
using System.Web.Mvc;
using MyProject.Models;

namespace MyProject.Controllers
{
    public class TodoController : Controller
    {
        private ApplicationDbContext db = new ApplicationDbContext();

        // GET: Todo
        public ActionResult Index()
        {
            return View(db.TodoItems.ToList());
        }

        // GET: Todo/Details/5
        public ActionResult Details(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            TodoItem todoItem = db.TodoItems.Find(id);
            if (todoItem == null)
            {
                return HttpNotFound();
            }
            return View(todoItem);
        }

        // GET: Todo/Create
        public ActionResult Create()
        {
            return View();
        }

        // POST: Todo/Create
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create([Bind(Include = "Title,Description,DueDate")] TodoItem todoItem)
        {
            if (ModelState.IsValid)
            {
                db.TodoItems.Add(todoItem);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(todoItem);
        }

        // GET: Todo/Edit/5
        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            TodoItem todoItem = db.TodoItems.Find(id);
            if (todoItem == null)
            {
                return HttpNotFound();
            }
            return View(todoItem);
        }

        // POST: Todo/Edit/5
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit([Bind(Include = "Id,Title,Description,DueDate")] TodoItem todoItem)
        {
            if (ModelState.IsValid)
            {
                db.Entry(todoItem).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            return View(todoItem);
        }

        // GET: Todo/Delete/5
        public ActionResult Delete(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            TodoItem todoItem = db.TodoItems.Find(id);
            if (todoItem == null)
            {
                return HttpNotFound();
            }
            return View(todoItem);
        }

        // POST: Todo/Delete/5
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public ActionResult DeleteConfirmed(int id)
        {
            TodoItem todoItem = db.TodoItems.Find(id);
            db.TodoItems.Remove(todoItem);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                db.Dispose();
            }
            base.Dispose(disposing);
        }
    }
}

    此控制器包含了所有CRUD操作。

创建视图

  1. 在Views文件夹中，创建一个名为Todo的文件夹。

  2. 在Todo文件夹中，创建以下视图：

    • Index.cshtml
    • Details.cshtml
    • Create.cshtml
    • Edit.cshtml
    • Delete.cshtml

    每个视图的代码如下：

    • Index.cshtml

      @model List<MyProject.Models.TodoItem>

<h2>Todo Items</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>

<table class="table">
    <tr>
        <th>
            #
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Title)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Description)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.DueDate)
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.Id)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Title)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Description)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.DueDate)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.Id }) |
            @Html.ActionLink("Details", "Details", new { id=item.Id }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.Id })
        </td>
    </tr>
}

</table>

    • Details.cshtml

      @model MyProject.Models.TodoItem

<h2>Details</h2>

<table class="table">
    <tr>
        <th>
            #
        </th>
        <td>
            @Html.DisplayFor(model => model.Id)
        </td>
    </tr>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Title)
        </th>
        <td>
            @Html.DisplayFor(model => model.Title)
        </td>
    </tr>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Description)
        </th>
        <td>
            @Html.DisplayFor(model => model.Description)
        </td>
    </tr>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.DueDate)
        </th>
        <td>
            @Html.DisplayFor(model => model.DueDate)
        </td>
    </tr>
</table>

<p>
    @Html.ActionLink("Edit", "Edit", new { id=Model.Id }) |
    @Html.ActionLink("Back to List", "Index")
</p>

    • Create.cshtml

      @model MyProject.Models.TodoItem

<h2>Create</h2>

@using (Html.BeginForm()) {
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>TodoItem</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.Title, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Title, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Title, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(model => model.Description, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Description, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Description, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(model => model.DueDate, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.DueDate, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.DueDate, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

    • Edit.cshtml

      @model MyProject.Models.TodoItem

<h2>Edit</h2>

@using (Html.BeginForm()) {
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>TodoItem</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.Title, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Title, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Title, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(model => model.Description, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Description, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Description, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(model => model.DueDate, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.DueDate, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.DueDate, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Update" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

    • Delete.cshtml

      @model MyProject.Models.TodoItem

<h2>Delete</h2>

<h3>Are you sure you want to delete this?</h3>
<div>
    <h4>TodoItem</h4>
    <hr />
    <dl class="dl-horizontal">
        <dt>
            #
        </dt>
        <dd>
            @Html.DisplayFor(model => model.Id)
        </dd>
        <dt>
            @Html.DisplayNameFor(model => model.Title)
        </dt>
        <dd>
            @Html.DisplayFor(model => model.Title)
        </dd>
        <dt>
            @Html.DisplayNameFor(model => model.Description)
        </dt>
        <dd>
            @Html.DisplayFor(model => model.Description)
        </dd>
        <dt>
            @Html.DisplayNameFor(model => model.DueDate)
        </dt>
        <dd>
            @Html.DisplayFor(model => model.DueDate)
        </dd>
    </dl>

    @using (Html.BeginForm()) {
        @Html.AntiForgeryToken()

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Delete" class="btn btn-danger" />
                @Html.ActionLink("Cancel", "Index")
            </div>
        </div>
    }
</div>
运行应用程序

  1. 在Visual Studio中，按下F5键运行应用程序。

  2. 浏览器将打开应用程序，显示一个包含所有待办事项的列表页面。

  3. 在列表页面中，单击“Create New”按钮，创建一个新的待办事项。

  4. 通过编辑和删除按钮，对待办事项进行更改和删除。