CheckedChanged事件不起作用

Question

I have make a structure like this:

• Topic 1
  • Topic A
    • Topic α
    • Topic β
  • Topic B
    • Topic γ
    • Topic δ
• Topic 2
  • Topic C
    • Topic ε
    • Topic ζ
  • Topic D
    • Topic η
    • Topic θ

First comes topics 1 and 2 on screen. By checking one of them Topic A and B or C and D comes on screen. Finally coms α until θ on screen dependent on the chosen letters. I do this with the following code:

ASP.NET

<asp:ScriptManager EnablePartialRendering="true" runat="server" />

<div>
    <asp:UpdatePanel ID="updPnlTopics" UpdateMode="Always" runat="server">
        <ContentTemplate>

            <asp:Panel ID="pnlNumbers" CssClass="topics" runat="server" />
            <asp:Panel ID="pnlLetters" CssClass="topics" runat="server" />
            <asp:Panel ID="pnlRoman" CssClass="topics" runat="server" />

        </ContentTemplate>
    </asp:UpdatePanel>

</div>

C#

private List<TopicNumbers> _allTopics;
private TopicNumber _topicNumber;

protected async void Page_Load(object sender, EventArgs e)
{
    await LoadTopics();
}

private async Task LoadTopics()
{
    _allTopics = await GetAllTopics(); //this gets all topics from database

    foreach (TopicNumber number in _allTopics)
    {
        MakeRadioButton<TopicNumber>(number, pnlNumbers, new EventHandler(rbtNumber_CheckedChanged));
    }
}

private void rbtNumber_CheckedChanged(object sender, EventArgs e)
{
    RadioButton rbt = (RadioButton)sender; // 1 ● --> stop always

    pnlLetters.Controls.Clear();
    pnlRomain.Controls.Clear();

    if (rbt.Checked)
    {
        _topicNumber = (from number in _allTopics
                        where number.Naam == rbt.Text
                        select number).First<TopicNumber>();

        foreach (TopicLetter letter in _topicNumber.Letters) //Letters contains a list with all the letters for that number
        {
            MakeRadioButton<TopicLetter>(letter, pnlLetters, new EventHandler(rbtLetter_CheckedChanged));
        }
    }
}

public void rbtLetter_CheckedChanged(object sender, EventArgs e)
{
    RadioButton rbt = (RadioButton)sender; // 2 ● --> don't stop

    pnlRoman.Controls.Clear();

    if (rbt.Checked)
    {
       TopicLetters letter = (from letter in _topicNumber.Letters
                              where letter.Naam == rbt.Text
                              select letter).First<TopicLetters>();

       foreach (TopicRomain romain in letter.Romans) //contains a list with all roman letters for that western letter
       {
            RadioButton rbtRoman = new RadioButton() {
                Text = roman.ToString(),
                GroupName = "roman",
                AutoPostBack = true
            };

            pnlRoman.Controls.Add(rbtRoman);

            pnlRoman.Controls.Add(new Literal() {
                Text = "<br/>"
            });
        }
    }
}

private void MakeRadioButton<T>(T type, Panel pnl, EventHandler evt)
{
    RadioButton rbt = new RadioButton() {
        Text = type.ToString(),
        GroupName = pnl.ID,
        ID = type.ToString(),
        AutoPostBack = true,
        CssClass = "topic"
    };

    rbt.CheckedChanged += evt;

    //\\
    updPnlCategorieen.Triggers.Add(new AsyncPostBackTrigger() {
        ControlID = rbt.ID,
        EventName = "CheckedChanged"
    });

    pnl.Controls.Add(rbt);

    pnl.Controls.Add(new Literal() {
        Text = "<br/>"
    });
}

---

Now my problem is when I will show the roman letters. My code looks to be good (think I), but rbtLetter_CheckedChanged never runs. I've place two breakpoints (see ● in code), but the compiler always stops on the first one and never by the second one.

Some images for explain it better:

1. First state = beginning state: (only numbers are show) ok

   

   I check one of the numbers.

2. Second state: (only numbers and letters are show) ok

   

   I check one of the letters.

3. Third state: (numbers, letters and roman must be show) error

   

---

Edit: august 15, 2015

I've also try to add a trigger on the UpdatePanel everytime a Checkbox is created.

This is my code that I used for it (stands //\\\\ on code above) .

updTopics.Triggers.Add(new AsyncPostBackTrigger()
{
    ControlID = rbtNumber.ID, // or rbtLetter
    EventName = "CheckedChanged"
});

But it is always the same problem that the roman and the letters are deleted.

---

Edit: august 27, 2015

Anyone (on another community) said me that there is a page life cycle . Now I know why this code is not working. But I don't know how to solve this.

I know this question is too broad, but can anyone help me or give me a hint for my problem? I will test it if your idea works. I'm really new with ASP.net.
Thanks for all help and sorry for my poor english.

Answer 1

On the way you have develop it, goes it never work. UpdatePanel s can not be used for that. An alternative you can use are user controls. and into that control can UpdatePanel s work.