MVC初体验-EF系列（状态跟踪的修改）（21） -云博客

MVC初体验-EF系列（状态跟踪的修改）（21）

# 前端 2024-05-05 06:18 0 24 来源：云博客

主要就是在没有AddOrUpdate方法的时候，你想要改变数据库内的一条数据如何操作

核心操作（这里主要展示下如何只改变一个字段“ShipName”的值）

（改变整条记录的值在Attach后面操作db.Entry(order).State = EntityState.Modified;然后savechange即可，但是注意这样操作是将新建的order对象对应的字段全部替换了）

[HttpPost] public ActionResult Edit() { int orderID = int.Parse(HttpContext.Request["orderID"]); string shipName = HttpContext.Request["shipname"]; Orders order = new Orders { OrderID = orderID,ShipName = shipName }; db.Set<Orders>().Attach(order); db.Entry(order).Property("ShipName").IsModified = true; db.Entry(order).Property("ShipName").CurrentValue = shipName; db.SaveChanges(); return Redirect("/Orders/Edit/?id="+orderID); }

后台代码：

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Mvc;using System.Data.Entity;using T1_EF.Models;namespace T1_EF.Controllers{ public class OrdersController : Controller { DbContext db = new NorthwindEntities(); // GET: Orders public ActionResult Index() { var list = from order in db.Set<Orders>() select order; ViewData.Model = list; return View(); } public ActionResult Edit(int id) { var data = db.Set<Orders>().Where(o=>o.OrderID==id).FirstOrDefault(); ViewData.Model = data; return View(); } [HttpPost] public ActionResult Edit() { int orderID = int.Parse(HttpContext.Request["orderID"]); string shipName = HttpContext.Request["shipname"]; Orders order = new Orders { OrderID = orderID,ShipName = shipName }; db.Set<Orders>().Attach(order); db.Entry(order).Property("ShipName").IsModified = true; db.Entry(order).Property("ShipName").CurrentValue = shipName; db.SaveChanges(); return Redirect("/Orders/Edit/?id="+orderID); } }}

View Code

前台代码Index.cshtml：

@model IEnumerable<T1_EF.Models.Orders>@{ Layout = null;}<!DOCTYPE html><html><head> <meta name="viewport" content="width=device-width" /> <title>Index</title></head><body> <div> <table border="1"> <tr> <td>订单编号</td> <td>客户名称</td> <td>船舶公司</td> <td>船名</td> <td>修改</td> </tr> @foreach (var item in Model) { <tr> <td>@item.OrderID</td> <td>@item.Customers.CompanyName</td> <td>@item.Shippers.CompanyName</td> <td>@item.ShipName</td> <td><a href="@Url.Action("Edit","Orders")?id=@item.OrderID">修改</a></td> </tr> } </table> </div></body></html>

View Code

Edit.cshtml：

@model T1_EF.Models.Orders@{ Layout = null;}<!DOCTYPE html><html><head> <meta name="viewport" content="width=device-width" /> <title>Edit</title></head><body> <div> <table border="1"> <tr> <td>@Model.OrderID</td> <td>@Model.Customers.CompanyName</td> <td>@Model.Shippers.CompanyName</td> <td>@Model.ShipName</td> </tr> </table> <form action="@Url.Action("Edit","Orders")" method="post"> <input type="hidden" name="orderID" value="@Model.OrderID"/> <input type="text" name="shipname" placeholder="修改ShipName的值" /> <input type="submit" name="change" value="修改ShipName" /> </form> </div></body></html>