单击按钮后无法访问动态创建的文本框的文本

Posted 2023-02-22

【中文标题】单击按钮后无法访问动态创建的文本框的文本

【英文标题】：Can not access text of dynamically created textbox after button click

【发布时间】：2020-11-05 20:23:51

【问题描述】：

我有问题。我有一个带有一个 ContentPlaceHolder 的 aspx 页面。在那个 ContentPlaceHolder 我有一个 div 和一个按钮，如下所示：

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">    
    <div id="divCustomCustomers" runat="server" >
    </div>
    <asp:Button runat="server" ID="btnInsert" Text="Insert" OnClick="btnInsert_OnClick" />    
</asp:Content>

在 PageLoad 上，我动态地将文本框控件添加到 divCustomCustomers，如下所示：

private void AddControls(string currentCustomer)

    var customTable = new Table();
    customTable.ID = "tableCustomCustomer_" + currentCustomer;

    var customTrHeaders = new TableRow();
    customTrHeaders.Cells.Add(new TableCell()  Text = "TextId" );

    customTable.Controls.Add(customTrHeaders);

    var customTableCells = new TableRow();

    var tableCellTextId = new TableCell();
    var textBoxTextId = new TextBox()  ID = "tbTextId_" + currentCustomer ;
    tableCellTextId.Controls.Add(textBoxTextId);

    customTableCells.Cells.Add(tableCellTextId);

    customTable.Controls.Add(customTableCells);

    divCustomCustomers.Controls.Add(customTable);

然后我在该文本框中输入一些随机文本 (var textBoxTextId = new TextBox() ID = "tbTextId_" + currentCustomer ;)。

当我单击按钮并调用函数 btnInsert_OnClick 时，我似乎无法获取文本框的文本。回发后，文本框消失了。我尝试通过以下方式获取文本框：

    protected void btnInsert_OnClick(object sender, EventArgs e)
    
        string currentCustomer = "sameCustomerAsWhenCreated";

        var control = divCustomCustomers.FindControl("tbTextId_" + currentCustomer) as TextBox;
        var control2 = divCustomCustomers.FindControl("ContentPlaceHolder1_tbTextId_" + currentCustomer) as TextBox;
        var control3 = this.FindControl("tbTextId_" + currentCustomer) as TextBox;
        var control4 = this.FindControl("ContentPlaceHolder1_tbTextId_" + currentCustomer) as TextBox;
    

我也尝试过使用我读到的 FindControl 方法：

    protected void btnInsert_OnClick(object sender, EventArgs e)
    
        string currentCustomer = "sameCustomerAsWhenCreated";

        var control = FindControl(this.Controls, "tbTextId_" + currentCustomer);
    

    private Control FindControl(ControlCollection controlCollection, string name)
    
        foreach (Control control in controlCollection)
        
            if (control.ID.ToLower() == name.ToLower() || control.ClientID.ToLower() == name.ToLower())
            
                return control;
            

            if (control.Controls.Count > 0)
            
                Control result = FindControl(control.Controls, name);
                if (result != null)
                
                    return result;
                
            
        

        return null;
    

但没有任何效果，我无法控制和使用文本。你们能帮帮我吗？请！

【参考方案1】：

如果没有回发，您是否运行了 AddControls()？

在页面加载时总是运行 AddControls()，你应该从文本框中获取文本。

我在 aspx 中添加了一个 Literal，下面是我的 aspx.cs 中的代码

<div id="divCustomCustomers" runat="server" >
</div>
<asp:Button runat="server" ID="btnInsert" Text="Insert" OnClick="btnInsert_Click" />   
<hr />
<asp:Literal ID="ltResult" runat="server"></asp:Literal>


protected void Page_Load(object sender, EventArgs e)

    //Don't run AddControls only in first load.
    //if (this.IsPostBack)
    //
    //    AddControls("sameCustomerAsWhenCreated");
    //

    AddControls("sameCustomerAsWhenCreated");


protected void btnInsert_Click(object sender, EventArgs e)

    string currentCustomer = "sameCustomerAsWhenCreated";
    var control = divCustomCustomers.FindControl("tbTextId_" + currentCustomer) as TextBox;

    this.ltResult.Text = "control: " + control.Text + "<br>";

Here is my test result