关于asp.net:C# – MVC应用程序如何更新和删除数据库中的记录

C# - MVC application How to update and delete a record from the database

我需要知道如何更新和删除数据库中的记录。我知道如何添加记录，但无法更新和删除数据库中的记录。

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namespace Ex.Models
{
using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;

public partial class MyEntities : DbContext
{
public MyEntities()
: base("name= MyEntities")
{
}

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}

public DbSet<Friend> Friend { get; set; }
}
}

——

控制器

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// POST: /Home/Edit/5
[HttpPost]
public ActionResult Edit(int id, Friend f)
{
try
{
// TODO: Add update logic here
myEntities.Friend.Attach(f);// Doesn't work.. How to update ?
myEntities.SaveChanges();
return RedirectToAction("Index");
}
catch
{
return View();
}
}

为了向数据库添加记录，我使用了以下代码。它奏效了；

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myEntities.Friend.Add(f);
myEntities.SaveChanges();
return RedirectToAction("Index");

更新

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<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Exp.Models.Friend>" %>

    Delete
</asp:Content>

Delete

Are you sure you want to delete?
<fieldset>
    <legend>Friend</legend>

    Name
   
        <%: Html.DisplayFor(model => model.Name) %>
   

</fieldset>
<% using (Html.BeginForm()) { %>
    <p>

        <input type="submit" value="Delete" /> |
        <%: Html.ActionLink("Back to List","Index") %>
   
</p>
<% } %>

</asp:Content>

删除

1 2	myEntities.Friend.Remove(f); myEntities.SaveChanges();

更新

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Friend f = myEntities.Friend.FirstOrDefault(x => x.Id = MyId);
f.Name = NewName;
myEntities.SaveChanges();

相关讨论

在索引页中(用于删除和编辑的链接)

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编辑(第一个编辑功能是编辑页面，它获取特定ID的所有数据，第二个功能是保存更改。)

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public ActionResult Edit(Int32 StuID)
{
var studata = stu.Studs.Where(x => x.StudId == StuID).FirstOrDefault();
if (studata != null)
{
TempData["ID"] = StuID;
TempData.Keep();
return View(studata);
}
return View();
}
[HttpPost]
public ActionResult Edit(Stud stu1)
{
Int32 StuID = (int)TempData["ID"];
var studata = stu.Studs.Where(x => x.StudId == StuID).FirstOrDefault();
studata.StudName = stu1.StudName;
studata.StudAddress = stu1.StudAddress;
studata.StudEmail = stu1.StudEmail;
stu.ObjectStateManager.ChangeObjectState(studata,);
stu.SaveChanges();
return RedirectToAction("Index");
}

删除

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public ActionResult Delete(int StuID)
{
if (StuID > 0)
{
var studata = stu.Studs.Where(x => x.StudId == StuID).FirstOrDefault();
if (studata != null)
{
stu.DeleteObject(studata);
stu.SaveChanges();
}
}
return RedirectToAction("Index");
}

更新：第一条路

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public void IsActiveItem(int id)
{
var data = db.IRAS_InventoryItems.Find(id);
data.IsActive = false;
db.Entry(data).State = EntityState.Modified;
db.SaveChanges();
}

更新：第二种方法

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public void IsActiveItem(int id)
{
var data = (from a in db.IRAS_InventoryItems
where a.Id == id
select a).FirstOrDefault();
data.IsActive = false;
db.Entry(data).State = EntityState.Modified;
db.SaveChanges();
}

移除：首先

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public void Remove(int id)
{
var data = db.IRAS_InventoryItems.Find(id);
data.IsActive = false;
db.IRAS_InventoryItems.Remove(data);
db.SaveChanges();
}

删除：秒

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public void Remove(int id)
{
var data = (from a in db.IRAS_InventoryItems
where a.Id == id
select a).FirstOrDefault();
db.IRAS_InventoryItems.Remove(data);
db.SaveChanges();
}

只需proove的concept controller.updateModel不能有效地工作。

全班在这里https://stackoverflow.com/a/39452785/1071165

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const string PK ="Id";
protected Models.Entities con;
protected System.Data.Entity.DbSet<T> model;

[HttpPost]
public virtual ActionResult AddEdit(T item)
{
TestUpdate(item);

con.SaveChanges();

return RedirectToAction("Index");
}

[HttpGet]
public virtual ActionResult Remove(string id)
{
int nId = 0;
int.TryParse(id, out nId);
if (nId != 0)
{
var item = model.Find(nId);
con.Entry(item).State = System.Data.Entity.EntityState.Deleted;
con.SaveChanges();
}
return Redirect(Request.UrlReferrer.ToString());
}

private void TestUpdate(object item)
{
var props = item.GetType().GetProperties();
foreach (var prop in props)
{
object value = prop.GetValue(item);
if (prop.PropertyType.IsInterface && value != null)
{
foreach (var iItem in (System.Collections.IEnumerable)value)
{
TestUpdate(iItem);
}
}
}

int id = (int)item.GetType().GetProperty(PK).GetValue(item);
if (id == 0)
{
con.Entry(item).State = System.Data.Entity.EntityState.Added;
}
else
{
con.Entry(item).State = System.Data.Entity.EntityState.Modified;
}

}

更新：

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if (ModelState.IsValid && f != null)
{
myEntities.Friend.Attach(f);
var upd = (from c in myEntities.Friend
where c.Id == f.Id
select c).FirstOrDefault();
upd.Data1=f.Data1;
...
....
myEntities.ObjectStateManager.ChangeObjectState(f, EntityState.Modified);
myEntities.SaveChanges();
}

删除：

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if (ModelState.IsValid && f != null)
{
var del = (from c in myEntities.Friend
where c.Id == f.Id
select c).FirstOrDefault();

myEntities.Friend.DeleteObject(del);
myEntities.SaveChanges();
}