MVC应用程序如何从数据库中更新和删除记录

删除

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

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

要更新，它与添加相同，但没有.Friend.Add(f)。像这样加载条目:

var friendEntity = myEntites.Friend.SingleOrDefault(f => f.Id == id);
friendEntity.Field1 = f.Field1;
...
myEntities.SaveChanges();

要删除，使用.Add(f), .Remove的反面

更新:

      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:

   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();
        }

Just 概念验证控制器。UpdateModel不能正常工作。

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

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;
    }
}

Update:First Way

        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:第二个方法

           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();
           }

删除:首先

         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

              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();
               }

在索引页(删除和编辑链接)

<td>
            <%: Html.ActionLink("Edit","Edit", new{StuID=@item.StudId}) %>
        </td>
        <td>
            <%: Html.ActionLink("Delete","Delete", new{StuID=@item.StudId}) %>
         </td>

编辑(第一个编辑功能用于编辑页面，它取特定Id的所有数据，第二个功能用于保存更改)

 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");
    }

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");
    }