在UpdatePanel控件失去价值 [英] Control in UpdatePanel loses value

问题描述

我有两个组合框，第一个触发器的UpdatePanel，更新第二个：

 保护无效cb1_SelectedIndexChanged（对象发件人，EventArgs的发送）
        {        cb2.DataSource = DT1;
        cb2.DataBind（）;
         }
 

问题是，当我点击按钮，所有值都行，除了一个在UpdatePanel的，所以在UpdatePanel的子控件以某种方式重置选定的索引。

不知道如何解决这个问题？

我知道会话，但我不知道什么步骤CB2的值赋给会话。

感谢。

更新，ASPX

 ＆LT; ASP：的UpdatePanel ID =UpdatePanel1=服务器ChildrenAsTriggers =FALSE
                                                        的UpdateMode =条件＆GT;
    ＆LT; D​​X：ASPxComboBox ID =CB2=服务器HEIGHT =的22pxValueField =ID
                                                                值类型=System.Int32WIDTH =170像素＆GT;
                                                                ＆LT;柱体和GT;
                                                                    ＆LT; D​​X：ListBoxColumn标题=ID字段名=ID可见=FALSE/＆GT;
                                                                    ＆LT; D​​X：ListBoxColumn标题=城市字段名=城市/＆GT;
                                                                ＆LT; /专栏＆GT;
                                                            ＆LT; / DX：ASPxComboBox＆GT;
＆LT; /＆的ContentTemplate GT;
                                                    ＆LT;＆触发器GT;
                                                        ＆LT; ASP：AsyncPostBackTrigger
    控件ID =CB1事件名称=的SelectedIndexChanged/＆GT;
                                                        ＆LT; /触发器＆GT;
                                                    ＆LT; / ASP：的UpdatePanel＆GT;
 

解决方案

一对夫妇的事情在这里：你有 ChildrenAsTriggers =FALSE，但你们又异步回传trigeer对孩子的控制：CB2。我想你应该的删除的的 ChildrenAsTriggers =FALSE属性（true是默认值），你可能是指有ansync回传trigeer设置为'CB1'控制象下面这样：

 ＆LT; ASP：的UpdatePanel ID =UpdatePanel1=服务器的UpdateMode =条件＆GT;
    ＆LT;＆的ContentTemplate GT;
      ＆LT; D​​X：ASPxComboBox ID =CB2=服务器HEIGHT =的22pxValueField =ID
                       值类型=System.Int32WIDTH =170像素＆GT;
        ＆LT;柱体和GT;
           ＆LT; D​​X：ListBoxColumn标题=ID字段名=ID可见=FALSE/＆GT;
           ＆LT; D​​X：ListBoxColumn标题=城市字段名=城市/＆GT;
        ＆LT; /专栏＆GT;
    ＆LT; / DX：ASPxComboBox＆GT;
   ＆LT; /＆的ContentTemplate GT;
   ＆LT;＆触发器GT;
     ＆LT; ASP：AsyncPostBackTrigger控件ID =CB1事件名称=的SelectedIndexChanged/＆GT;
   ＆LT; /触发器＆GT;
  ＆LT; / ASP：的UpdatePanel＆GT;
 

此外我认为你原来的code复制失踪开幕＆LT;的ContentTemplate方式＆gt; 标签

在这一点上你的CB1控件的事件`cb1_SelectedIndexChanged'应该解雇，并能够在更新上述的UpdatePanel的CB2控件的数据源。

I have two comboboxes, first one triggers updatepanel that updates second one:

        protected void cb1_SelectedIndexChanged(object sender, EventArgs e)
        {

        cb2.DataSource = DT1;
        cb2.DataBind();


         }

Problem is, when I click button, all values are ok, except one in UpdatePanel, so updatepanel somehow resets selected index on child controls.

Any idea how to fix this?

I know about sessions, but I don't know on what step to assign value of cb2 to session.

Thanks.

Update, aspx

    <asp:UpdatePanel ID="UpdatePanel1" runat="server" ChildrenAsTriggers="False" 
                                                        UpdateMode="Conditional">
    <dx:ASPxComboBox ID="cb2" runat="server" Height="22px" ValueField="ID" 
                                                                ValueType="System.Int32" Width="170px">
                                                                <Columns>
                                                                    <dx:ListBoxColumn Caption="ID" FieldName="ID" Visible="False" />
                                                                    <dx:ListBoxColumn Caption="City" FieldName="City" />
                                                                </Columns>
                                                            </dx:ASPxComboBox>
</ContentTemplate>
                                                    <Triggers>
                                                        <asp:AsyncPostBackTrigger
    ControlID="cb1" EventName="SelectedIndexChanged" />
                                                        </Triggers>
                                                    </asp:UpdatePanel>

解决方案

A couple of things here: you have ChildrenAsTriggers="False", but yet you have an async postback trigeer for a child control: 'cb2'. I think you should remove the ChildrenAsTriggers="False" property ("true" is default value) and you probably meant to have the ansync postback trigeer set to the `cb1' control like below:

   <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional"> 
    <ContentTemplate>
      <dx:ASPxComboBox ID="cb2" runat="server" Height="22px" ValueField="ID"     
                       ValueType="System.Int32" Width="170px">  
        <Columns>
           <dx:ListBoxColumn Caption="ID" FieldName="ID" Visible="False" /> 
           <dx:ListBoxColumn Caption="City" FieldName="City" /> 
        </Columns>                                                             
    </dx:ASPxComboBox> 
   </ContentTemplate>                                                     
   <Triggers>                                                         
     <asp:AsyncPostBackTrigger ControlID="cb1" EventName="SelectedIndexChanged" />   
   </Triggers>                                                     
  </asp:UpdatePanel>

Also I think your original code copied was missing the opening <ContentTemplate> tag.

At this point your cb1 control's event `cb1_SelectedIndexChanged' should fire and be able to update the cb2 control's datasource in the UpdatePanel above.

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