CODEWITHSUNDEEP
c#asp.netbuttonevent-handling
gjohal
gjohal

Reputation: 21

Handling an event on a dynamically-added Button after postback

Basically, I have an update panel in which i have a link button, when user clicks on the link button all the contents are cleared and textbox shows up in which user enters something and when user hit enter key, the update panel should be refreshed or gets updated or repopulated with all the contents .

How can I do it ???

The way I am trying to do this is that when event handler of link button is fired, I created a hidden button dynamically and assign it a new event handler which will get fired when user hits enter key.This new dynamic button is created inside link button event handler. In this new button event handler I will repopulate the contents back.

The problem with my way is the event handler of dynamically created button is not fired. Why ???

Please try to answer in c#. Thanks in advance.

Regards,

My code #

    protected void Submit_Click1(object sender, EventArgs e)
    {
        Label1.Text = TextBox1.Text + TextBox2.Text + " are sucessfully registered";
        Button mento = new Button();
        mento.cssclass = "invisible";
        mento.Click += new EventHandler(mento_click);
        // here this new mento button is attached to update panel
        updatepanel1.ContentTemplateContainer.Controls.add(mento);
    }

Now the problem is mento_click event handler does not get fired ???

Upvotes: 0

Views: 2775

Answers (3)

netfed
netfed

Reputation: 601

To all of you strugling with postback from buttons in asp.net, I would like to mention an alternative and ancient method of dealing with button-click events.

1) name your dynamically created buttons using a Prefix (like for instance this one: btn_). That way, every button you create will have a name starting with this prefix. For example the first button you create will have the name btn_0. You can achieve this by a routine like this one:

For _counter As Integer = 0 To 3
Dim butt As New Button
' the next 1 line is convenient when programming for the .net 4.0 framework:
butt.ClientIDMode = UI.ClientIDMode.Static 
butt.butt.ID = "btn_" & _counter
butt.Text = "someting"
page.controls.add(butt)
next

2) ... and then, to handle it all, you can do it like this in the on_load event of your asp.net page:

If IsPostBack Then
    For Each key As String In Request.Form
        If InStr(Trim(key), "btn_") > 0 Then
            Response.Write(Request.Form(key))
        End If
    Next   
End If

Upvotes: 0

Pablo Lopez
Pablo Lopez

Reputation: 76

You have to attach the event on page_init or page_load every time theres a request, or the event wont get hooked up to the control.

you can check out this link to understand why:

http://msdn.microsoft.com/en-us/library/ms178472.aspx

Example

if you want to hook it up on the submit you should do something like:

   page_init(object sender, EventArgs e)
   {
      CreateControls();
   }

   private void CreateControls()
   {
       //Create button with event and add to the panel
   }

   clickEvent(object sender, EventArgs e)
   {
       updatePanel.Update();
   }

That should fire correctly the event. Im sorry i just wrote this on the fly and didnt test it, but i hope it gives you de general idea.

Cheers.

Upvotes: 0

Niklas
Niklas

Reputation: 1853

You can catch the enter key, in the textbox?

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        //add event keydown
        textBox1.KeyDown += new KeyEventHandler(textBox1_KeyDown);

    }
    void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        switch (e.KeyCode )
        {

            case Keys.Enter:
                //YOur updatecode here:
                MessageBox.Show("You press enter");
                break;

            default:
                break;
        }
    }
}

Upvotes: 1

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