Handle Event of button at runtime

[Ria12]

Hello.....I want to generate a button at runtime..and set the style like Top,Left,Right,Height,Width of a button also have to handle click event and when button is clicked it should redirect to another page.Plz help me.

[kunal pawar]

which type of button you want to generate at runtime, "server" side or HTML control.

If you want to generate html button then using
var btn = document.createElement("input");
btn.setAttribute("type","Button");
btn.className ="css class name";

For server control

Button btn = new Button();

[Ria12]

hi....I want to generate server button controls in Vb.net and also want to handle the click Event of that button.any help is appricated....

[Frinavale]

Please take a look at the article about how to use dynamic controls in ASP.NET.


You need to declare your Button at the page level (so that it is accessible to all of the page's methods). You need to declare this Button "WithEvents" in VB.NET

You need to instantiate the Button in the Page Init event (otherwise you will not be able to handle the click event).


For example:

Private WithEvents myButton As Button
 
Private Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
    myButton = new Button
    myButton.Height = 60
    myButton.Width = 100
    myButton.Style.Add("color","blue")
End Sub
 
Private Sub myButton _Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles myButton .Click
 
End Sub
 

-Frinny

[Ria12]

I used your code...but actually i want generate button on click of other button....

[Frinavale]

Well what do you have so far?
The example in the article explains how to show more TextBoxes depending on a DropDownList. This same concept would be applied to your button click...

[Ria12]

hi.......I 'm able to generate buttons on click of another botton in Vb.net but not able to handle button click event that is generated at runtime...

[Frinavale]

You have most likely instantiated the dynamic button during the OnClick event of the non-dynamic button. In this case the OnClick event for they dynamic button will not fire.

The reason is pretty simple, ASP.NET uses the ViewState to determine what event(s) caused the page to post back to the server (and to determine what state your Objects are in...like selected indexes of DropDownList etc). If your Object does not exist (is not instantiated) at the time the ViewState is loaded, then your event will not be registered and all the state information for that Object will be lost.

Therefore you need to instantiate your button during the Page Init event.

So, you need to be able to indicate when to create the button during the Page Init event. In order to do this you need to store a Boolean value somewhere that is available during the Page Init event. Because the Page Init event occurs before the ViewState is loaded you are going to have to use something that is available through the Request Object...

You could use a hidden field, or a cookie, or the URL...

[Ria12]

I understand your point with that i solve my problem of Click Event of runtime generated button not fired ....now i want to retrieve the height of rutime generated button pass to another page but it create an error

can not implicitly convert type unit to integer

my code is

   Select Case hidden
 
                    Case "Top"
                        id= 1
                        For i As Integer = 0 To c - 1
 
                            Dim btnTop As Button = New Button()
                            btnTop.ID = id
                            btnTop.Text = "Top"
                            'btnTop.Style("Top") = "200px"
                            btnTop.CssClass = "btnTop"
                            'btnTop.Style("Left") = "5px"
                            btnTop.Style("Height") = h & "px"
                            btnTop.Style("Width") = w & "px"
                            btnTop.Style("Border") = "solid"
                            Panel1.Controls.Add(btnTop)
                            AddHandler btnTop.Click, AddressOf btnTop_Click
                            id= id + 1
 
 
                        Next i
      End Select

Event handler of this button is

 Private Sub btnTop_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        l = Integer.Parse(DirectCast(sender, Button).ID)
        text= CType(sender, Button).Text
        height=CType(sender,Button).Height
        Session("ID") = l
        Session("loc") = text
        Session("height1")=height
        Response.Redirect("Default2.aspx")

Plz help me, I urgently need help....