动态创建的按钮不会触发其点击事件

Question

I have a dynamic page that contains a panel with included content. I add a new panel on a button click. With a button within the dynamically added panel, the click event is not firing.

Here is code for the form:

<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>

            <asp:Panel ID="MainPanel" runat="server">
            </asp:Panel>

</div>
</form>

This is the code that creates some panels and a child button ( step_button ):

public partial class _Default : System.Web.UI.Page
{


    Button button = new Button() { Text="Add level1"};
    static int controls = 1;



    private List<ActionPanel> PanelsList
    {
        get
        {
            if (Session["DataActionsPanels"] == null)
                Session["DataActionsPanels"] = new List<ActionPanel>();
            return (List<ActionPanel>)Session["DataActionsPanels"];
        }
    }


    protected void Page_Load(object sender, EventArgs e)
    {
        button.Click += new EventHandler(button_Click);
        button.Attributes.Add("style", "float:right;");
        button.ID = "button1";
        MainPanel.Controls.Add(button);


        if (IsPostBack)
        {
            RestorePanels();
            return;
        }
        AddActionPanel();

    }



    protected void RestorePanels()
    {
        foreach (ActionPanel panel in PanelsList)
            AddActionPanel(panel);
    }




    protected void button_Click(object sender, EventArgs e)
    {
        controls++;            
        AddActionPanel(); 
    }


    protected void AddActionPanel()
    {
        var panel = new ActionPanel(controls, ScriptManager1);
        PanelsList.Add(panel);
        var button_index = MainPanel.Controls.IndexOf(button);
        MainPanel.Controls.AddAt(button_index, panel.GetPanel());
    }

    protected void AddActionPanel(ActionPanel panel)
    {
        var button_index = MainPanel.Controls.IndexOf(button);
        MainPanel.Controls.AddAt(button_index, panel.GetPanel());
    }
}


public class ActionPanel
{

    private Panel main_panel = new Panel();
    private TextBox data_action_id_box = new TextBox();
    private TextBox data_action_name_box = new TextBox();
    private TextBox data_action_error_box = new TextBox() ;
    Button step_button = new Button() { Text = "Add level2"};
    private Panel steps_panel = new Panel();
    private List<StepPanel> steps_list = new List<StepPanel>();
    private int step_count = 1;
    private ScriptManager _manager;
    public ActionPanel(int i, ScriptManager manager)
    {

        _manager = manager;
        main_panel.Attributes.Add("style", "float:left; width:100%");
        main_panel.GroupingText = "TestLevel  " + i;
        main_panel.Controls.Add(new Label() { Text = "TestLevel1" });
        data_action_id_box.Attributes.Add("style", "margin-left:13px");
        main_panel.Controls.Add(data_action_id_box);
        main_panel.Controls.Add(new Literal() { Text = "<br></br>" });

        main_panel.Controls.Add(new Label() { Text = "TestLevel11" });
        data_action_name_box.Attributes.Add("style", "margin-left:10px");
        main_panel.Controls.Add(data_action_name_box);
        main_panel.Controls.Add(new Literal() { Text = "<br></br>" });

        main_panel.Controls.Add(new Label() { Text = "TestLevel11" });
        data_action_error_box.Attributes.Add("style", "margin-left:33px");
        main_panel.Controls.Add(data_action_error_box);
        main_panel.Controls.Add(new Literal() { Text = "<br></br>" });

        step_button.ID = "button2_"+i;
        step_button.Click += new EventHandler(AddStep_Click);
        step_button.Attributes.Add("style", "float:right;");
        steps_panel.Controls.Add(step_button);
        steps_panel.Load += new EventHandler(steps_panel_Load);
        main_panel.Controls.Add(steps_panel);

        main_panel.Load += new EventHandler(steps_panel_Load);

        steps_panel.Attributes.Add("style", "float:left; width:100%");
        AddStepPanel();

    }

    void steps_panel_Load(object sender, EventArgs e)
    {



    }

    public  void AddStep_Click(object sender, EventArgs e)
    {
        step_count++;
        AddStepPanel();
    }

    public Panel GetPanel()
    {

        return main_panel;
    }

    private void AddStepPanel()
    {
        var panel = new StepPanel(step_count);
        steps_list.Add(panel);
        var button_index = steps_panel.Controls.IndexOf(step_button);
        steps_panel.Controls.AddAt(button_index, panel.GetPanel());
    }

    private void AddStepPanel(StepPanel panel)
    {
        var button_index = steps_panel.Controls.IndexOf(step_button);
        steps_panel.Controls.AddAt(button_index, panel.GetPanel());
    }
}



public class StepPanel
{

    private Panel main_panel = new Panel();
    private DropDownList step_type_box = new DropDownList();
    private TextBox step_name_box = new TextBox();
    private TextBox step_error_box = new TextBox() ;
    private Panel step_panel = new Panel();

    public StepPanel(int i)
    {
        main_panel.Attributes.Add("style", "float:left; width:100%");
        main_panel.GroupingText = "TestLevel2 " + i;
        main_panel.Controls.Add(new Label() { Text = "TestLevel2" });

        step_type_box.Items.Add("TestLevel2");
        step_type_box.Items.Add("TestLevel22");
        step_type_box.Items.Add("TestLevel222");
        step_type_box.Items.Add("TestLevel2222");
        step_type_box.Attributes.Add("style", "margin-left:13px");

        main_panel.Controls.Add(step_type_box);

        var label1 = new Label() { Text = "TestLevel22" };
        label1.Attributes.Add("style","margin-left:20px;");
        main_panel.Controls.Add(label1);
        step_name_box.Attributes.Add("style", "margin-left:10px");
        main_panel.Controls.Add(step_name_box);

        var label2 = new Label() { Text = "TestLevel222" };
        label2.Attributes.Add("style", "margin-left:20px;");
        main_panel.Controls.Add(label2);
        step_error_box.Attributes.Add("style", "margin-left:33px");
        main_panel.Controls.Add(step_error_box);

    }

    public Panel GetPanel()
    {

        return main_panel;
    }

}

How can I make this work?

Answer 1

You are adding your panels onload , do it on init or preinit . This is microsoft's recommendation.

Answer 2

I solve my problem.

My mistake that i use panels saved in Session. All dynamic controls must be recreated in Postback.

So i update method "AddActionPanel(ActionPanel panel)":

    protected void AddActionPanel(ActionPanel panel)
    {
        var count = PanelsList.IndexOf(panel);
        var panel1 = new ActionPanel(count, ScriptManager1);

        var button_index = DataActionsPanel.Controls.IndexOf(button);
        DataActionsPanel.Controls.AddAt(count, panel1.GetPanel());
    }