Question

问题：事件处理程序quantity_TextChanged不会更改会话变量“列表”以反映当前状态。事件处理程序将附加到addItemRowToTable生成的所有文本框中，并通过其分配的ID进行区分。

我肯定会丢失一些东西，但不确定。

其他信息：我需要这样一种方式：对多个文本框所做的更改都被保存到1个Session变量中，以供以后在会话中进一步使用（按表中显示的顺序）。然后，每个文本框的值将在其旁边的标签中使用（每个文本框1个标签）。

所需结果：

Header                      Header2 
[TextBox with value of 42]  [Label displaying 42]
[TextBox with value of 76]  [Label displaying 76]
[TextBox with value of 105] [Label displaying 105]

WebForm1.aspx.cs

protected void Page_LoadComplete(object sender, EventArgs e)
{
    if (Session["list"] != null)
    {
        List<int> numbers = Session["list"] as List<int>;
        int index = 0;
        foreach (int item in numbers)
        {
            tblItems.Rows.AddAt(index + 1, addItemRowToTable(item, index));
            // For debugging purposes
            Response.Write("<script>console.log(\"" + item.ToString() + "\");</script>");
            index++;
        }
    }

}

private TableRow addItemRowToTable(int item, int index)
{
    TableCell[] cells = { new TableCell(), new TableCell() };
    TableRow row = new TableRow();

    TextBox box = new TextBox();
    box.ID = String.Format("{0}_q", index);
    box.Attributes["type"] = "number";
    box.Attributes["min"] = "1";
    box.Attributes["width"] = "60px";
    box.TextChanged += new EventHandler(quantity_TextChanged);
    box.AutoPostBack = true;
    cells[0].Controls.Add(box);

    Label lbl = new Label();
    lbl.ID = String.Format("{0}_l", index);
    lbl.Text = item.ToString();
    cells[1].Controls.Add(lbl);

    foreach (TableCell cell in cells)
        row.Cells.Add(cell);
    return row;
}

protected void Button1_Click(object sender, EventArgs e)
{
    if (Session["list"] != null)
    {
        List<int> numbers = Session["list"] as List<int>;
        numbers.Add(0);
        Session["list"] = numbers;
    }
    else
    {
        List<int> numbers = new List<int>();
        numbers.Add(0);
        Session["list"] = numbers;
    }
}

private void quantity_TextChanged(object sender, EventArgs e)
{
    if (Session["list"] != null)
    {
        TextBox item = sender as TextBox;
        int position = Convert.ToInt32(item.ID.Split('_')[0]);

        List<int> numbers = Session["list"] as List<int>;
        numbers[position] = Convert.ToInt32(item.Text);
        Session["list"] = numbers;
    }
}

WebForm1.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="Assignment2.WebForm1" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
        <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
        <br />
        <br />
        <asp:Table ID="tblItems" runat="server">
            <asp:TableHeaderRow>
                <asp:TableHeaderCell>Header</asp:TableHeaderCell>
                <asp:TableHeaderCell>Header2</asp:TableHeaderCell>
            </asp:TableHeaderRow>
        </asp:Table>
        </div>
    </form>
</body>
</html>

Answer 1

首先，您不需要进入Page_LoadComplete。我认为您可能试图在单击按钮后添加正确数量的文本框。但是单击按钮应该只添加一个新的TextBox，仅此而已。在Page_Load中，您需要添加存储在Session中的TextBox。请参见下面的示例，获取具有TextChanged事件的可行解决方案，该事件之所以有效，是因为所有正确的控件都是在回发时重新创建的。

protected void Page_Load(object sender, EventArgs e)
{
    if (IsPostBack == false)
    {
        //do not add or manipulate dynamic controls inside an ispostback check
    }

    //check if the session exists
    if (Session["list"] != null)
    {
        //add the correct number of textboxes from session
        for (int i = 1; i <= Convert.ToInt32(Session["list"]); i++)
        {
            addTextBox(i);
        }
    }
}


private void addTextBox(int index)
{
    //create a new textbox
    TextBox tb = new TextBox();
    tb.ID = "DynamicTextBox" + index;
    tb.AutoPostBack = true;

    //add an event to the textbox
    tb.TextChanged += new EventHandler(quantity_TextChanged);

    //add the textbox to the page
    PlaceHolder1.Controls.Add(tb);
}


protected void Button1_Click(object sender, EventArgs e)
{
    int index = 1;

    //get the current textbox count if it exists
    if (Session["list"] != null)
    {
        index = Convert.ToInt32(Session["list"]) + 1;
    }

    //add a new textbox
    addTextBox(index);

    //upate the session with the new value
    Session["list"] = index;
}


private void quantity_TextChanged(object sender, EventArgs e)
{
    //display the textbox value in a label for testing
    Label1.Text = ((TextBox)sender).Text;
}

事件处理程序不会更改Label中的文本

1 个答案: