无涯教程-ASP.NET Core - Razor表单在本章中，无涯教程将继续讨论标签助手，还将在应用程序中添加新功能

在本章中，无涯教程将继续讨论标签助手，还将在应用程序中添加新功能，并使其能够编辑现有员工的详细信息，将在每个员工添加一个链接，该链接将转到HomeController上的Edit动作。

@model HomePageViewModel  
@{  
   ViewBag.Title = "Home"; 
} 
<h1>Welcome!</h1> 
<table>
@foreach (var employee in Model.Employees) {
<tr>
<td>@employee.Name</td>
     </span><span class="str">&lt;td&gt;</span><span class="pln"> 
        </span><span class="pun">&lt;</span><span class="pln">a asp</span><span class="pun">-</span><span class="pln">controller </span><span class="pun">=</span><span class="pln"> </span><span class="str">"Home"</span><span class="pln"> asp</span><span class="pun">-</span><span class="pln">action </span><span class="pun">=</span><span class="pln"> </span><span class="str">"Details"</span><span class="pln"> 
           asp</span><span class="pun">-</span><span class="pln">routeid </span><span class="pun">=</span><span class="pln"> </span><span class="str">"@employee.Id"</span><span class="pun">&gt;</span><span class="typ">Details</span><span class="pun">&lt;/</span><span class="pln">a</span><span class="pun">&gt;</span><span class="pln"> 
        
        </span><span class="pun">&lt;</span><span class="pln">a asp</span><span class="pun">-</span><span class="pln">controller </span><span class="pun">=</span><span class="pln"> </span><span class="str">"Home"</span><span class="pln"> asp</span><span class="pun">-</span><span class="pln">action </span><span class="pun">=</span><span class="pln"> </span><span class="str">"Edit"</span><span class="pln"> 
           asp</span><span class="pun">-</span><span class="pln">routeid </span><span class="pun">=</span><span class="pln"> </span><span class="str">"@employee.Id"</span><span class="pun">&gt;</span><span class="typ">Edit</span><span class="pun">&lt;/</span><span class="pln">a</span><span class="pun">&gt;</span><span class="pln"> 
           
     </span><span class="pun">&lt;/</span><span class="pln">td</span><span class="pun">&gt;</span><span class="pln"> 
  </span><span class="pun">&lt;/</span><span class="pln">tr</span><span class="pun">&gt;</span><span class="pln"> 

}
</table>

还没有"Edit"操作，但是需要一个可以编辑的员工ID。因此，首先通过右键单击 Views→Home 文件夹并选择 Add→New Items 创建新视图。

在中间窗格中，选择" MVC View Page"；调用页面Edit.cshtml。现在，单击添加按钮。

在 Edit.cshtml 文件中添加以下代码。

@model Employee 
@{ 
   ViewBag.Title = $"Edit {Model.Name}"; 
} 
<h1>Edit @Model.Name</h1>  
<form asp-action="Edit" method="post">
<div>
<label asp-for = "Name"></label>
<input asp-for = "Name" />
<span asp-validation-for = "Name"></span>
</div>
<div>
<input type = "submit" value = "Save" />
</div>
</form>

对于此页面的标题，可以说无涯教程要编辑然后提供员工姓名。

转到HomeController类，并添加 Edit 操作，该操作返回为用户提供表单以编辑员工的视图的视图，然后将需要第二个Edit操作，该操作将响应HttpPost，如下所示。

[HttpGet] 
public IActionResult Edit(int id) { 
   var context = new FirstAppDemoDbContext(); 
   SQLEmployeeData sqlData = new SQLEmployeeData(context); 
   var model = sqlData.Get(id); 
if (model == null) {
return RedirectToAction("Index");
}
return View(model);
}

首先，需要一个可以响应GET请求的编辑操作，这将需要一个员工ID，这里的代码将类似于" Details"操作中的代码，将首先提取用户要编辑的员工的数据，还需要确保该雇员确实存在，如果不存在，会将用户重定向回Index视图，当有员工存在时，将渲染"Edit"视图。

还需要响应表单将发送的HttpPost。

在HomeController.cs文件中添加一个新类，如以下程序所示。

public class EmployeeEditViewModel { 
   [Required, MaxLength(80)] 
   public string Name { get; set; } 
}

以下是"Edit"操作的实现。

[HttpPost] 
public IActionResult Edit(int id, EmployeeEditViewModel input) { 
   var context = new FirstAppDemoDbContext(); 
   SQLEmployeeData sqlData = new SQLEmployeeData(context); 
   var employee = sqlData.Get(id); 
if (employee != null && ModelState.IsValid) {
employee.Name = input.Name;
context.SaveChanges();

return RedirectToAction("Details", new { id = employee.Id });
}
return View(employee);
}

根据路由规则，应始终从在URL中具有ID的URL交付编辑表单，如/home/edit/1 。

将名称从"input"视图模型复制到从数据库中检索到的员工，并保存更改，SaveChagnes()方法将把所有这些更改刷新到数据库中。

以下是HomeController的完整实现。

using Microsoft.AspNet.Mvc; 
using FirstAppDemo.ViewModels;
using FirstAppDemo.Services;
using FirstAppDemo.Entities;
using FirstAppDemo.Models;
using System.Collections.Generic;
using System.Linq;
using System.ComponentModel.DataAnnotations;
namespace FirstAppDemo.Controllers {
public class HomeController : Controller {
public ViewResult Index() {
var model = new HomePageViewModel();
using (var context = new FirstAppDemoDbContext()) {
SQLEmployeeData sqlData = new SQLEmployeeData(context);
model.Employees = sqlData.GetAll();
}

return View(model);
}

public IActionResult Details(int id) {
var context = new FirstAppDemoDbContext();
SQLEmployeeData sqlData = new SQLEmployeeData(context);
var model = sqlData.Get(id)
     </span><span class="kwd">if</span><span class="pln"> </span><span class="pun">(</span><span class="pln">model </span><span class="pun">==</span><span class="pln"> </span><span class="kwd">null</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
        </span><span class="kwd">return</span><span class="pln"> </span><span class="typ">RedirectToAction</span><span class="pun">(</span><span class="str">"Index"</span><span class="pun">);</span><span class="pln"> 
     </span><span class="pun">}</span><span class="pln"> 
     </span><span class="kwd">return</span><span class="pln"> </span><span class="typ">View</span><span class="pun">(</span><span class="pln">model</span><span class="pun">);</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln"> 
  </span><span class="pun">[</span><span class="typ">HttpGet</span><span class="pun">]</span><span class="pln"> 
  </span><span class="kwd">public</span><span class="pln"> </span><span class="typ">IActionResult</span><span class="pln"> </span><span class="typ">Edit</span><span class="pun">(</span><span class="kwd">int</span><span class="pln"> id</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     </span><span class="kwd">var</span><span class="pln"> context </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">FirstAppDemoDbContext</span><span class="pun">();</span><span class="pln"> 
     </span><span class="typ">SQLEmployeeData</span><span class="pln"> sqlData </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">SQLEmployeeData</span><span class="pun">(</span><span class="pln">context</span><span class="pun">);</span><span class="pln"> 
     </span><span class="kwd">var</span><span class="pln"> model </span><span class="pun">=</span><span class="pln"> sqlData</span><span class="pun">.</span><span class="typ">Get</span><span class="pun">(</span><span class="pln">id</span><span class="pun">);</span><span class="pln"> 
        
     </span><span class="kwd">if</span><span class="pln"> </span><span class="pun">(</span><span class="pln">model </span><span class="pun">==</span><span class="pln"> </span><span class="kwd">null</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
        </span><span class="kwd">return</span><span class="pln"> </span><span class="typ">RedirectToAction</span><span class="pun">(</span><span class="str">"Index"</span><span class="pun">);</span><span class="pln"> 
     </span><span class="pun">}</span><span class="pln"> 
     </span><span class="kwd">return</span><span class="pln"> </span><span class="typ">View</span><span class="pun">(</span><span class="pln">model</span><span class="pun">);</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln">  
  </span><span class="pun">[</span><span class="typ">HttpPost</span><span class="pun">]</span><span class="pln"> 
  </span><span class="kwd">public</span><span class="pln"> </span><span class="typ">IActionResult</span><span class="pln"> </span><span class="typ">Edit</span><span class="pun">(</span><span class="kwd">int</span><span class="pln"> id</span><span class="pun">,</span><span class="pln"> </span><span class="typ">EmployeeEditViewModel</span><span class="pln"> input</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     </span><span class="kwd">var</span><span class="pln"> context </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">FirstAppDemoDbContext</span><span class="pun">();</span><span class="pln"> 
     </span><span class="typ">SQLEmployeeData</span><span class="pln"> sqlData </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">SQLEmployeeData</span><span class="pun">(</span><span class="pln">context</span><span class="pun">);</span><span class="pln"> 
     </span><span class="kwd">var</span><span class="pln"> employee </span><span class="pun">=</span><span class="pln"> sqlData</span><span class="pun">.</span><span class="typ">Get</span><span class="pun">(</span><span class="pln">id</span><span class="pun">);</span><span class="pln"> 
     
     </span><span class="kwd">if</span><span class="pln"> </span><span class="pun">(</span><span class="pln">employee </span><span class="pun">!=</span><span class="pln"> </span><span class="kwd">null</span><span class="pln"> </span><span class="pun">&amp;&amp;</span><span class="pln"> </span><span class="typ">ModelState</span><span class="pun">.</span><span class="typ">IsValid</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
        employee</span><span class="pun">.</span><span class="typ">Name</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> input</span><span class="pun">.</span><span class="typ">Name</span><span class="pun">;</span><span class="pln"> 
        context</span><span class="pun">.</span><span class="typ">SaveChanges</span><span class="pun">();</span><span class="pln">  
        </span><span class="kwd">return</span><span class="pln"> </span><span class="typ">RedirectToAction</span><span class="pun">(</span><span class="str">"Details"</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> id </span><span class="pun">=</span><span class="pln"> employee</span><span class="pun">.</span><span class="typ">Id</span><span class="pln"> </span><span class="pun">});</span><span class="pln"> 
     </span><span class="pun">}</span><span class="pln"> 
     </span><span class="kwd">return</span><span class="pln"> </span><span class="typ">View</span><span class="pun">(</span><span class="pln">employee</span><span class="pun">);</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln"> 

}
public class SQLEmployeeData {
private FirstAppDemoDbContext _context { get; set; }
public SQLEmployeeData(FirstAppDemoDbContext context) {
_context = context;
}
public void Add(Employee emp) {
_context.Add(emp);
_context.SaveChanges();
}
public Employee Get(int ID) {
return _context.Employees.FirstOrDefault(e => e.Id == ID);
}
public IEnumerable<Employee> GetAll() {
return _context.Employees.ToList<Employee>();
}
}
public class HomePageViewModel {
public IEnumerable<Employee> Employees { get; set; }
}
public class EmployeeEditViewModel {
[Required, MaxLength(80)]
public string Name { get; set; }
}
}

编译程序并运行应用程序。

现在，有一个"Edit"链接；通过单击"Edit"链接来编辑Josh的详细信息。

将名称更改为Josh Groban。

单击保存按钮。

您可以看到名称已更改为Josh Groban，如上面的屏幕截图所示。现在单击"Home"链接。

在主页上，您现在将看到更新的名称。

无涯教程-ASP.NET Core - Razor表单

参考链接