我意识到应该在 Page_Load 和 Page_Init 中创建动态控件，以便将它们注册到控件树中。
我创建了一个自定义控件，需要在按钮 OnClick 事件中使用 ViewState。然后使用此 ViewState 动态创建控件。
由于生命周期将进行:页面加载 -> 按钮点击 -> 页面预渲染。在“单击按钮”之前， View 状态不会更新，因此我在 Page PreRender 中创建动态控件。但是，创建按钮并以编程方式在 Page_PreRender 中分配 OnClick EventHandler 不起作用。
有谁知道我怎样才能让它工作？
btn_DeleteTableRow_Click 不会触发。这是在 CreatePartRows() 中设置的
这是我的例子:
<asp:UpdatePanel ID="up_RMAPart" runat="server" UpdateMode="Conditional" EnableViewState="true" ChildrenAsTriggers="true">
<ContentTemplate>
<div class="button" style="width: 54px; margin: 0px; float: right;">
<asp:Button ID="btn_AddPart" runat="server" Text="Add" OnClick="btn_AddPart_Click" />
</div>
<asp:Table ID="Table_Parts" runat="server" CssClass="hor-zebra">
</asp:Table>
<div class="clear"></div>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btn_AddPart" EventName="Click" />
</Triggers>
代码隐藏:
[Serializable]
public struct Part
{
public string PartName;
public int Quantity;
public int PartID;
public Part(string sPartName, int iQuantity, int iPartID)
{
PartName = sPartName;
Quantity = iQuantity;
PartID = iPartID;
}
}
public partial class RMAPart : System.Web.UI.UserControl
{
private Dictionary<string,Part> m_RMAParts;
private int m_RowNumber = 0;
public Dictionary<string, Part> RMAParts
{
get
{
if (ViewState["m_RMAParts"] != null)
return (Dictionary<string, Part>)ViewState["m_RMAParts"];
else
return null;
}
set
{
ViewState["m_RMAParts"] = value;
}
}
public int RowNumber
{
get
{
if (ViewState["m_RowNumber"] != null)
return Convert.ToInt32(ViewState["m_RowNumber"]);
else
return 0;
}
set
{
ViewState["m_RowNumber"] = value;
}
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
RMAParts = new Dictionary<string, Part>();
RowNumber = 0;
RMAParts.Add("PartRow_" + RowNumber.ToString(), new Part());
RowNumber = 1;
CreatePartRows();
}
}
protected void Page_PreRender(object sender, EventArgs e)
{
CreatePartRows();
}
private void CreatePartRows()
{
Table_Parts.Controls.Clear();
TableHeaderRow thr = new TableHeaderRow();
TableHeaderCell thc1 = new TableHeaderCell();
thc1.Controls.Add(new LiteralControl("Part"));
thr.Cells.Add(thc1);
TableHeaderCell thc2 = new TableHeaderCell();
thc2.Controls.Add(new LiteralControl("Quantity"));
thr.Cells.Add(thc2);
TableHeaderCell thc3 = new TableHeaderCell();
thc3.Controls.Add(new LiteralControl(""));
thr.Cells.Add(thc3);
Table_Parts.Rows.Add(thr);
foreach (KeyValuePair<string, Part> kvp in RMAParts)
{
string[] sKey = kvp.Key.Split('_');
TableRow tr = new TableRow();
tr.ID = kvp.Key;
TableCell tc1 = new TableCell();
TextBox tb_Part = new TextBox();
tb_Part.ID = "tb_Part_" + sKey[1];
tb_Part.CssClass = "textbox1";
tc1.Controls.Add(tb_Part);
tr.Cells.Add(tc1);
TableCell tc2 = new TableCell();
TextBox tb_Quantity = new TextBox();
tb_Quantity.ID = "tb_Quanitty_" + sKey[1];
tb_Quantity.CssClass = "textbox1";
tc2.Controls.Add(tb_Quantity);
tr.Cells.Add(tc2);
TableCell tc3 = new TableCell();
Button btn_Delete = new Button();
btn_Delete.ID = "btn_Delete_" + sKey[1];
btn_Delete.CommandArgument = tr.ID;
btn_Delete.Click += new EventHandler(btn_DeleteTableRow_Click);
btn_Delete.Text = "Remove";
tc3.Controls.Add(btn_Delete);
tr.Cells.Add(tc3);
Table_Parts.Rows.Add(tr);
}
}
public void Reset()
{
Table_Parts.Controls.Clear();
RMAParts.Clear();
RowNumber = 0;
RMAParts.Add("PartRow_" + RowNumber.ToString(), new Part());
RowNumber = 1;
CreatePartRows();
}
protected void btn_AddPart_Click(object sender, EventArgs e)
{
RMAParts.Add("PartRow_" + RowNumber.ToString(), new Part());
RowNumber++;
}
protected void btn_DeleteTableRow_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
TableRow tr = (TableRow)Table_Parts.FindControl(btn.CommandArgument);
Table_Parts.Rows.Remove(tr);
RMAParts.Remove(btn.CommandArgument);
}
}
最佳答案
为确保输入字段的值在回传中保持不变并引发服务器事件:
- 使用 View 状态来跟踪动态创建的控件。
- 在
LoadViewState中重新创建具有相同 ID 的控件(不是Load或PreRender，因为那时输入字段的值将丢失)。
此答案的其余部分详细说明了我如何修改您的代码以使其正常工作。
RMAPart.ascx
为方便起见，您可以在 .ascx 中声明标题行:
<asp:Table ID="Table_Parts" runat="server" CssClass="hor-zebra">
<asp:TableRow>
<asp:TableHeaderCell Text="Part" />
<asp:TableHeaderCell Text="Quantity" />
<asp:TableHeaderCell />
</asp:TableRow>
</asp:Table>
RMAPart.ascx.cs
要跟踪动态创建的行，请在 View 状态中维护行 ID 列表:
public partial class RMAPart : System.Web.UI.UserControl
{
private List<string> RowIDs
{
get { return (List<string>)ViewState["m_RowIDs"]; }
set { ViewState["m_RowIDs"] = value; }
}
在 btn_AddPart_Click 处理程序中，生成一个新行 ID 并为新行创建控件:
protected void btn_AddPart_Click(object sender, EventArgs e)
{
string id = GenerateRowID();
RowIDs.Add(id);
CreatePartRow(id);
}
private string GenerateRowID()
{
int id = (int)ViewState["m_NextRowID"];
ViewState["m_NextRowID"] = id + 1;
return id.ToString();
}
private void CreatePartRow(string id)
{
TableRow tr = new TableRow();
tr.ID = id;
TableCell tc1 = new TableCell();
TextBox tb_Part = new TextBox();
tb_Part.ID = "tb_Part_" + id;
tb_Part.CssClass = "textbox1";
tc1.Controls.Add(tb_Part);
tr.Cells.Add(tc1);
TableCell tc2 = new TableCell();
TextBox tb_Quantity = new TextBox();
tb_Quantity.ID = "tb_Quantity_" + id;
tb_Quantity.CssClass = "textbox1";
tc2.Controls.Add(tb_Quantity);
tr.Cells.Add(tc2);
TableCell tc3 = new TableCell();
Button btn_Delete = new Button();
btn_Delete.ID = "btn_Delete_" + id;
btn_Delete.CommandArgument = id;
btn_Delete.Click += btn_DeleteTableRow_Click;
btn_Delete.Text = "Remove";
tc3.Controls.Add(btn_Delete);
tr.Cells.Add(tc3);
Table_Parts.Rows.Add(tr);
}
在 btn_DeleteTableRow_Click 处理程序中，删除被点击的行并更新 View 状态:
protected void btn_DeleteTableRow_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
TableRow tr = (TableRow)Table_Parts.FindControl(btn.CommandArgument);
Table_Parts.Rows.Remove(tr);
RowIDs.Remove(btn.CommandArgument);
}
Hook Page_Load 并通过创建第一行开始:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Reset();
}
}
public void Reset()
{
while (Table_Parts.Rows.Count > 1)
Table_Parts.Rows.RemoveAt(Table_Parts.Rows.Count - 1);
ViewState["m_NextRowID"] = 0;
string id = GenerateRowID();
RowIDs = new List<string> { id };
CreatePartRow(id);
}
覆盖 LoadViewState 并使用存储在 View 状态中的 ID 重新创建行:
protected override void LoadViewState(object savedState)
{
base.LoadViewState(savedState);
foreach (string id in RowIDs)
{
CreatePartRow(id);
}
}
}
处理零件
上面的代码根本没有使用您的 Part 结构。要在您的业务对象和用户控件之间实际移动数据，您可以添加一个采用 Part 集合并使用它来创建行和填充文本框的公共(public)方法，然后添加另一个公共(public)方法读取将文本框的值输出到 Part 集合中。
关于asp.net - 基于viewstate在Page_PreRender中创建动态控件导致按钮OnClick事件不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17755263/