c# - SaveChanges 后如何从数据库更新缓存的 EF？

Question

场景如下 - 不同的用户通过从网页的下拉列表中选择一个值来进行更改。下拉列表包含在 DataView 中或通过构建表格。如果用户 A 对第 1 行进行了更改，它会更新数据库并在重新绑定(bind)后显示他们的更改。随后，当用户 A 进行更改并更改第 2 行时，用户 B 在同一页面上。更新数据库并重新绑定(bind) GridView (或重建表)。但是用户 B 看不到用户 A 所做的更改。我假设这是由于 EF 缓存。如果用户刷新页面(或被重定向回页面)，他们可以看到数据库中的最新数据。

如何在不刷新页面的情况下从数据库获取最新数据？

每次在 PageLoad 中调用绑定(bind)的方法，包括回传:

    private void PopulateFormForDealer(DateTime BeginDate, DateTime EndDate, int DealerID, bool UnVerifiedOnly)
    {
        try
        {                
        using (var DB = new NIMSModel.NIMSEntities())
        {

    var scheduledOrders = from r in DB.Reservations
              join o in DB.Orders on r.ResID equals o.ReservationID
              where r.ResDate <= EndDate && r.ResDate >= BeginDate && r.Claimed == "Y"
              && r.DealerID == DealerID //&& r.Verified == VerifiedOnly
              orderby r.ResDate, r.ResID
              select new { r.ResID, o.ID, o.VantiveOrderID, o.CustomerFirstName, o.CustomerCity, o.CustomerState, o.CustomerZipCode, o.OrderType.Type, r.ResDate, r.TimeOfDay, r.Source, DealerInstallerID = r.DealerInstallerID == null ? 0 : r.DealerInstallerID, r.Verified, r.Notes };


    GridView1.DataSource = scheduledOrders.ToList();
    GridView1.DataBind();

}
}
catch (Exception ex)
{
LogError(ex);
}

这是下拉列表的事件处理程序:

    protected void ddInstaller_SelectedIndexChanged(Object sender, EventArgs e)
    {
        try
        {
string foo = ((DropDownList)sender).SelectedValue;
Guid theg = new Guid(((DropDownList)sender).SelectedValue.Split('_')[1].ToString());
int? installerid = int.Parse(((DropDownList)sender).SelectedValue.Split('_')[0].ToString());
string installername = ((DropDownList)sender).SelectedItem.Text;

if (installerid == 0)
{
    installerid = null;
}

int testvalidguidlen = theg.ToString().Replace("0", "").Length;
if (testvalidguidlen > 10)
{
    string note;
    using (var DB = new NIMSModel.NIMSEntities())
    {
    var reservatoins = DB.Reservations.Where(r => r.ResID == theg).FirstOrDefault();

    if (reservatoins.DealerInstallerID != installerid)
    {
        var orders = DB.Orders.Where(o => o.ReservationID == theg).FirstOrDefault();

        reservatoins.DealerInstallerID = installerid;
        orders.InstallerID = installerid;

        if (reservatoins.Notes == null || reservatoins.Notes.Length >= 1800)
        {
        note = "[" + DateTime.Now.ToString("yyyy.MM.dd hh:mm:ss") + "] TechChange by: " + PTNAccount.UserName + "(" + PTNAccount.LoginID + "); NewTech: " + installername + ";";
        }
        else
        {
        note = reservatoins.Notes + "[" + DateTime.Now.ToString("yyyy.MM.dd hh:mm:ss") + "] TechChange by: " + PTNAccount.UserName + "(" + PTNAccount.LoginID + "); NewTech: " + installername + ";";
        }
        reservatoins.Notes = note;

        DB.SaveChanges();
    }
    }
}
}
catch (Exception ex)
{
LogError(ex);
}

这里是我们构建下拉列表的方法:

    private DropDownList PopulateInstallerDropDownList(DropDownList ddl, String resID)
    {

try
{
using (var DB = new NIMSModel.NIMSEntities())
{
    var DealerInstallers = from di in DB.DealerInstallers
               where di.Active == 1 && di.IsDeleted == "N" && di.DealerID == DealerID
               orderby di.Name
               select new { di.ID, di.Name };
    var DealerInstallersArray = DealerInstallers.ToArray();
    ListItem li = new ListItem("","0_" + resID);
    ddl.Items.Add(li);

    foreach (var installer in DealerInstallersArray)
    {
    ddl.Items.Add(new ListItem(installer.Name.ToString(), (installer.ID.ToString() + (string)"_" + resID.ToString())));
    }
}
}
catch (Exception ex)
{
string foo = ex.Message;
}
return ddl;

这是 RowDataBound 事件处理程序:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{

if (e.Row.RowType == DataControlRowType.DataRow)
{
string reservationID = DataBinder.Eval(e.Row.DataItem, "ResID").ToString();
DropDownList ddl = (DropDownList)e.Row.FindControl("ddInstaller");
PopulateInstallerDropDownList(ddl, reservationID);
string dealerInstallerId = DataBinder.Eval(e.Row.DataItem, "DealerInstallerID").ToString();

if (dealerInstallerId != "0")
{
    dealerInstallerId = dealerInstallerId + "_" + reservationID;
}

if (dealerInstallerId.Length > 1)
{
    ddl.SelectedIndex = ddl.Items.IndexOf(ddl.Items.FindByValue(dealerInstallerId));
}
}
}

过去两天我多次搜索解决方案。感谢您的帮助。

Answer 1

Entity Framework 3.5 以令人难以置信的方式保存更改，但它在 EF 4.0 中已修复我猜你使用的是 EF 3.5

悬停你需要知道你的数据发生了什么以及 EF 如何保存数据。你可以阅读 MSDN关于这个问题。

现在您可以在保存更改时调用刷新方法来更新数据。

context.Refresh(RefreshMode.ClientWins, orders);

英孚 4.0 > 英孚 3.5