Firing server side events at client side codes

mehdi62b · #1 (**permalink**) April 1st, 2005, 04:52 AM

Hi Experts,

I have a simple WebForm it has a TextBox

my TextBox has OnChange Event and its AutoPostBack property is true,

now what I want to accomplish is to make a Button to raise this event for me at client side(with javascript)

when I view the source of my ASP.NET page it is something like bellow,

Code:

<script language="javascript">
<!--
    function __doPostBack(eventTarget, eventArgument) {
        var theform;
        if (window.navigator.appName.toLowerCase().indexOf("netscape") > -1) {
            theform = document.forms["Form1"];
        }
        else {
            theform = document.Form1;
        }
        theform.__EVENTTARGET.value = eventTarget.split("$").join(":");
        theform.__EVENTARGUMENT.value = eventArgument;
        theform.submit();
    }
// -->
</script>

            <input type="submit" name="Button1" value="Button" id="Button1" />
            <button id="mahdi" type="button" language="javascript" onclick="document.Form1.TextBox1.onchange();">
                mehdi</button>
            <input name="TextBox1" type="text" onchange="__doPostBack('TextBox1','')" language="javascript" id="TextBox1" />

            <span id="Label1">Label</span>
        </form>

what I did ,I made a simple button(runat=server) and for its onclick I execute the TextBox onchange attribute

this is the tag I used for my button to raise the server side event,

<button id="mahdie" type="button" onclick="document.Form1.TextBox1.onchange();">

now when I test my page the OnChange event at server side doesn't fire

any opinion?

Thanks in advance.

_____________
Mehdi.
software student.

Santhi · #2 (**permalink**) April 1st, 2005, 06:52 AM

Hi Mehdi
Add attributes for the textbox control.
(eg) ctlTextbox.Attributes.Add("onChange","javascript:s omefunction();")

mehdi62b · #3 (**permalink**) April 1st, 2005, 07:49 AM

Santhi,
Thanks for the reply,
what I wanted is somewhat strange,

I want to raise TextBox1_TextChanged event(server side event) when user clicks on Button
at client-side codes(I mean I want to launch a server side event from the client side codes)

this is the tag I use in my ASP.NET page
<button id="mahdi" type="button" language="javascript" onclick="document.Form1.TextBox1.onchange();">

when user clicks on the button document.Form1.TextBox1.onchange() will be executed
so __doPostBack('TextBox1','') would be executed so there would be a postback but
when this postback occures just Page_Load fires other server side events like TextBox1_TextChanged doesn't fire.

_____________
Mehdi.
software student.

mehdi62b · #4 (**permalink**) April 1st, 2005, 08:48 AM

figuroud out,
well,it was clear,because I didn't change the value of textbox

<button id="mahdi" type="button" language="javascript"
onclick="document.Form1.TextBox1.value='somethingn ew';document.Form1.TextBox1.onchange();">

now TextBox1_TextChanged event is fired.

_____________
Mehdi.
software student.

planoie · #5 (**permalink**) April 13th, 2005, 10:46 PM

Mehdi,

Despite the appearance that the onChange event should result in the server-side event being fired, it doesn't. The server event fires when it sees an actual change in the textbox value as you've found.

I'm not clear on what you are trying to accomplish with this button, but why not use a regular asp:button that would supply its own postback event?

-Peter

mehdi62b · #6 (**permalink**) April 14th, 2005, 05:46 AM

yes,

because asp:button is rendered to submit button and there was no onclick attribute

<input type="submit" name="Button" value="Button" id="Button" />

so after that I added an onclick attribute to my asp:button

Button.Attributes.Add("onclick","__doPostBack('But ton','')");

so it would be rendered

<input type="submit" name="Button" value="Button" id="Button" onclick="__doPostBack('Button','')" style="height:0px;width:0px;"/>

I worked with button click event instead of text changed event.

_____________
Mehdi.
software student.

digitalman · #7 (**permalink**) May 18th, 2005, 09:11 AM

Well, if what you want is to have the button trigger your onchange event server-side, do something like the following (syntax may be slightly different...programming from memory)

private function mytextbox_TextChanged(sender as System.Object, e as System.EventArgs) handles mytextbox.TextChanged
    ' do my text change stuff here
end function

private function mybutton_Click(sender as System.Object, e as System.EventArgs) handles mybutton.Click
    ' Call the textbox's onchange event
    mytextbox_TextChanged(sender, e)
end function

What this does is when the button is pressed, it calls the textbox's textchanged event. It technically does not raise the textchanged event, but hey...it works. :D

Need to download code?

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