这个问题反复在论坛出现,其实这个问题在MSDN上早就有答案
1。英文版:Top Questions about the DataGrid Web Server Control(Mike Pope and Nikhil Kothari)
2。中文版:DataGrid Web 伺服器控制项的常见问题
1。英文版:Top Questions about the DataGrid Web Server Control(Mike Pope and Nikhil Kothari)
2。中文版:DataGrid Web 伺服器控制项的常见问题
可惜,论坛上的风气不太好,你即使给了连接,真正去看的人大概并不多
诀窍是,如果动态添加了列的话,需要在下一次PostBack时,在LoadViewState或更早把这些列重新添加。原因是,在Page类递归调用LoadViewState时,会调用DataGrid的CreateChildControls,而DataGrid的(实际上是它的父类的实现)CreateChildControls会调用DataGrid的CreateControlHierarchy()方法。在其中,DataGrid会根据当前的列的数目构造DataGridItem里的东西,然后从ViewState里恢复原来的数据。如果你没有重新添加你的动态列的话,你的动态列在PostBack后就会消失,更不用谈触发列里的控件的事件了
检验你的动态控件在PostBack后是否还在的一个方法是,加一个按钮看PostBack后的行为
下面是一个简单的测试
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<html>
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<body>
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<form runat="server">
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<asp:DataGrid id="DataGrid1" runat="server"
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GridLines="Both" AutoGenerateColumns="false"
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OnItemCommand="DataGrid1_ItemCommand">
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<Columns>
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<asp:ButtonColumn HeaderText="Static Button" Text="Click Me"
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CommandName="Static"/>
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<asp:TemplateColumn HeaderText="Data">
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<ItemTemplate><%#Container.DataItem%></ItemTemplate>
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</asp:TemplateColumn>
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</Columns>
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</asp:DataGrid>
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<asp:Button id="btnAddAColumn" runat="server" Text="Add a column" OnClick="AddButtonColumn"/>
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<asp:Button id="btnRefresh" runat="server" Text="Refresh" />
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</form>
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</body>
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</html>
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<script language="C#" runat="server">
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void BindGrid()
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{
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DataGrid1.DataSource = new string[] {"a","b","c"};
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DataGrid1.DataBind();
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}
26![](/Images/OutliningIndicators/InBlock.gif)
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void Page_Load(object sender, EventArgs e)
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{
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if (!IsPostBack)
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{
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BindGrid();
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}
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}
34![](/Images/OutliningIndicators/InBlock.gif)
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void DataGrid1_ItemCommand(Object sender, DataGridCommandEventArgs e)
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{
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Response.Write("ItemCommand is called<BR>");
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LinkButton btn = e.CommandSource as LinkButton;
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if (btn != null)
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Response.Write(String.Format("{0} is clicked on row {1}", btn.CommandName, e.Item.ItemIndex));
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}
43![](/Images/OutliningIndicators/InBlock.gif)
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//lifted from the original post
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public void CreateGridColumn(DataGrid OperationDataGrid)
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{
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ButtonColumn NewButCol = new ButtonColumn() ;
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NewButCol.Text = "编辑" ;
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NewButCol.HeaderText = "操作" ;
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NewButCol.CommandName = "Edit" ;
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NewButCol.ButtonType = ButtonColumnType.LinkButton;
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NewButCol.Visible = true ;
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OperationDataGrid.Columns.Add(NewButCol) ;
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//OperationDataGrid.Columns.AddAt(1,NewButCol) ;
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}
56![](/Images/OutliningIndicators/InBlock.gif)
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bool ButtonAdded
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{
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get {
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object o = ViewState["ButtonAdded"];
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if (o == null)
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return false;
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else return (bool)o;
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}
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set { ViewState["ButtonAdded"] = value;}
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}
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void AddButtonColumn(object sender, EventArgs e)
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{
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CreateGridColumn(DataGrid1);
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ButtonAdded = true;
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BindGrid();
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btnAddAColumn.Visible = false;
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}
75![](/Images/OutliningIndicators/InBlock.gif)
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protected override void LoadViewState(object savedState)
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{
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base.LoadViewState(savedState);
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//在这里重新添加,假如已经添加的话
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if (ButtonAdded)
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CreateGridColumn(DataGrid1);
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}
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</script>
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