Question

问题是： 在回发时，该表没有动态创建的行，rowcount为0。

点击按钮，它应检测动态生成的表格中的已选中复选框。
当使用下拉列表选择“日期”并使用日历选择“开始日期”时，表格由代码生成。

我知道有很多代码，但它是我认为必须发布的最少的代码，因此回答者可以调试。请注意我已经努力但无法得到解决方案。

以下是代码：

public partial class DaySelection : System.Web.UI.Page
{
    Table table1 = new Table();
    Button button1 = new Button();
    string the_id_checkbox;
    string the_id_label;
    //The need of the table ENDS
    DropDownList selectdays = new DropDownList();
    Label theselecteddate = new Label();
    Button extract_the_selected = new Button();
    Literal selected_values=new Literal();
    int number_of_row = -1;
    protected void Page_Load(object sender, EventArgs e)
    {
        CheckBox check_or_not = new CheckBox();
        try
        {
            selected_values.Text = "";
            form1.Controls.Remove(selected_values);
            form1.Page.Response.Write("inside try");
            for (int i = 0; i < table1.Rows.Count; i++)
            {
                Response.Write("inside for");
                the_id_checkbox = "checkmate" + i;
                the_id_label = "The_text" + i;
                check_or_not = (CheckBox)table1.Rows[i].FindControl(the_id_checkbox);
                if (check_or_not.Checked == true)
                {
                    form1.Page.Response.Write("inside if");
                    selected_values.Text = selected_values.Text + "<br /> " + check_or_not.Checked.ToString();
                    selected_values.Text = selected_values.Text + "  and the day is:  " + ((Label)table1.Rows[i].FindControl(the_id_label)).Text;
                }
                else
                {
                    Response.Write(" selection no detect");
                }
            }
            form1.Controls.AddAt(1, selected_values);
            Response.Write(selected_values.Text);
        }
        catch (NullReferenceException nn)
        {
            form1.Page.Response.Write("inside catch" + nn.Message.ToString() + nn.StackTrace);
        }
        extract_the_selected.Text = "Extract it";
        form1.Controls.AddAt(2,extract_the_selected);
        selectdays.AutoPostBack = true;
        ArrayList thedays = new ArrayList();
        thedays.Add("Monday" + DateTime.Now);
        thedays.Add("Tuesday");
        thedays.Add("Wednesday");
        thedays.Add("Thursday");
        thedays.Add("Friday");
        thedays.Add("Saturday");
        thedays.Add("Sunday");
        selectdays.DataSource = thedays;
        selectdays.DataBind();
        form1.Controls.AddAt(3,selectdays);
        Calendar1.SelectionChanged += new EventHandler(Calendar1_SelectionChanged);
    }

    void Calendar1_SelectionChanged(object sender, EventArgs e)
    {
        DateTime startdate;
        string month;
        month = Calendar1.SelectMonthText;
        startdate = Calendar1.SelectedDate;
        days_date(startdate);
    }

    void selectdays_SelectedIndexChanged(object sender, EventArgs e)
    {
        display_dates_of_day(DateTime.Parse("9-1-2010"), DateTime.Parse("9-30-2010"), selectdays.SelectedItem.Text);
    }

    public void days_date(DateTime startdate)
    {
        int noofdays;
        DateTime enddate = new DateTime();
        noofdays = DateTime.DaysInMonth(startdate.Year, startdate.Month) - 1;
        enddate = startdate.AddDays(noofdays);
        Response.Write("<br /> end date is  " + enddate);
        Response.Write("<br /> start date is " + startdate);
        display_dates_of_day( startdate, enddate, selectdays.SelectedItem.Text);
    }

    void display_dates_of_day(DateTime startDate, DateTime endDate, string selectedday)
    {
        int Count = 0;
        for (DateTime dt = startDate; dt <= endDate; dt = dt.AddDays(1.0))
        {
            if (dt.DayOfWeek.ToString() == selectedday)
            {
                table1.ID = "table1";
                number_of_row = number_of_row + 1;
                string date = dt.Date.ToString("dd-MMMM-yyyy");
                for (int adding_rows = 0; adding_rows < 1; adding_rows++)
                {
                    TableRow table_row1 = new TableRow();
                    TableCell table_cell1 = new TableCell();
                    TableCell table_cell2 = new TableCell();
                    Label The_label = new Label();
                    CheckBox checkmate = new CheckBox();
                    The_label.Text = date + " (<---date)" + number_of_row;
                    the_id_checkbox = "checkmate" + number_of_row;
                    checkmate.ID = the_id_checkbox;
                    the_id_label = "The_text" + number_of_row;
                    The_label.ID = the_id_label;
                    table_cell2.Controls.Add(checkmate);
                    table_cell1.Controls.Add(The_label);
                    table_row1.Controls.AddAt(0, table_cell1);
                    table_row1.Controls.AddAt(1, table_cell2);
                    table1.Rows.Add(table_row1);
                }
                button1.Text = "click me to export the value";
                form1.Controls.Add(table1);
                form1.Controls.AddAt(1, selected_values);
                Count++;
            }
        }
        Response.Write("<br /> The count of days by traversing:  " + Count);
    }
}

Answer 1

您看到这种看似“奇怪”的行为的原因是您正在动态构建Table1的内容并将其添加到.Controls中的display_dates_of_day个网页集中方法，由：

调用

selectdays_SelectedIndexChanged
Calendar1_SelectionChanged（间接）

这意味着当您在回发后重新构建页面时，控件不存在。如果您在浏览器中“查看源代码”，您会发现在单击按钮触发回发后，您无法在标记中找到字符串“Table1”，但如果您在单击日期后执行此操作日历，你可以。那是因为在“点击按钮”方案中，控件永远不会填充并添加到页面

我会提出一些建议来解决这个问题并解决问题：

从简化版本开始，以帮助您了解asp.net page lifecycle及其对您正在做的事情的影响。
尽量确保您的代码动态添加尽可能少的控件，因为这会让事情变得更加简单。即使Table1成为.aspx页面中声明的控件。

为什么回帖后Table1的行变为空？

1 个答案: