Found this question on an interview siteGiven the following methods of the ASP .Net Page class, in which of them would you attach an event handler to an event published by a control on the web page?
View 1 RepliesI have a question connected with controls and event handling. Lets say I want to create a LinkButton.
protected void loadLinkButton()
{
ContentPlaceHolder content = (ContentPlaceHolder)this.Master.FindControl("MainContent");
LinkButton lnk = new LinkButton();
lnk.ID = "lnikBtn";
lnk.Text = "LinkButton";
lnk.Click += new System.EventHandler(lnk_Click);
content.Controls.Add(lnk);
}
Here is the event handler:
protected void lnk_Click(object sender, EventArgs e)
{
Label1.Text = "ok!";
}
If I run the loadLinkButton function inside Page_Load everything is ok. But when I try to run the loadLinkButton by clicking simple button, link button is created but event is not handled.
protected void Button1_Click(object sender, EventArgs e)
{
loadLinkButton();
}
I there any way to solve it? Or loadLinkButton must always regenerated on Page_Load, Page_init etc.
Is there a technical reason for the existence of Page.PreLoad or is this just convenience to have a place where you can neatly place code that always have to be executed before the Load code? Is there a difference between adding code in the PreLoad event handler and adding code at the top of the Load event handler? And what would be a typical scenario where you use PreLoad?
View 2 RepliesI understand the order the events occur with page life cycle but it is not helping with my situation. I have a checkboxlist that is populated by a directory filled with forms. When I check a box next to the name of the form I would like it to dynamically create a wizard step and insert the form.
Order of events:
OnInit:
GatherForms() - Checks directory and loads all form names into checkbox
LoadForms() - Checks "Selected" Session and loads forms that were collected
CheckBoxList:SelectedIndexChanged #AutoPost = true#
PopulateForms() - Loops through the checkboxs and adds them to session state
When the user clicks the checkbox it does a postback and hits the OnInit which pulls from the session. The problem is that PopulateForms() was not ran yet so it populated nothing even though it is checked. If I click another item it will postback and appear. I cannot seem to be able to pull any kind of useful information from the checkbox before the refresh which means I cannot see the forms appear immediately. I have also tried looping the checkbox but unfortunately viewstate hasnt posted yet. sigh.
P.S: I cannot use Request.Form[] because I have to get all the selected items out of the checkbox. maybe i can but i cannot find a way :/
Using vb.net/asp.net 2005.
I have a page books.aspx that has a control named authors.ascx.
Inside the authors control there is a "select" button I want to add some kind of listener or event handler (not sure of the correct terminology) so on the parent page (books.aspx) I can respond to the "select" button being clicked.
I have to pass the authorID from the user control to the parent page.
In my authors.ascx control I just created this event:
[Code]....
Now I need to write the function for SelectAuthorBtnClick and I think add some kind of listener in the parent page to listen and handle the event.
I got an event handler like this, in this event, i wanted to call another button click event. How can I do that?
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if (ds.Tables[0].Rows.Count == 0)
I have a Silverlight control on page which has a upload control. the silverlight exposes some events such as
StartUpload() => To start the file upload,
StopUpload() => To stop the file upload if running,
CheckFileStatus() => to check the status of the file upload.
The page has aspx Submit button with onclientclick event and ocClick event.
<asp:Button ID="btn_upload" Text="External Upload" runat="server" OnClientClick="Javascript:StartUpload();"
OnClick="btn_upload_Click" />
When I click on the aspx Submit Button, the file selected in Silverlight control should be uploaded and after the completion of upload, the Server side event should get called.
i have two frames in a page. the fist one contains buttons the second one the form. i want to call an event from the second one after clicking a button in the first one ,
View 3 RepliesThis event handler is not responding at all to the click event. On click, the pagination numbers disappear and I'm not able to trace it in the debugger because the event handle doesn't even fire so I have no idea what's going on.
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I want to add more controls to page based on some specific conditions. Those controls don't need any ViewState or binding data, it is as simple as a static link. I wonder where I could write the code: inside OnLoad or OnInit method? and why? If I place it inside OnLoad, should I add following line: if (IsPostBack) return; before any initialization code?
View 4 RepliesI am using C#.
I am having below code in C#:
protected override void OnInit(EventArgs e)
{
try
{
if (Session["boolSignOn"].ToString() == "true".ToString())
{
lblPanelOpen.Text = Session["panelOpen"].ToString();
}
else
{
lblPanelOpen.Text = Session["panelOpen"].ToString();
}
}
catch (Exception ex)
{
Logger.Error("Error processing request:" + ex.Message);
}
}
protected override void OnLoad(EventArgs e)
{
try
{
if (!string.IsNullOrEmpty(Session["panelOpen"].ToString()))
{
lblPanelOpen.Text = string.Empty;
Session.Remove("panelOpen");
}
}
catch (Exception ex)
{
Logger.Error("Unable to remove the session variable:" + ex.Message);
}
}
In above code I am having a Session["panelOpen"] variable which is created from another user control and once my page is trying to render, I am storing Session["panelOpen"] in my hidden lblPanelOpen.Text on page OnInit() method, however when page is loaded completely then I am trying to remove the session variable.
I have a hidden control and i am adding oninit event from code behind on hidden control,but why does server side hiddenfield not fire oninit event?
Code:
<input type="hidden" runat="server" id="hidden" name="hiddenColConfigure"/>
Code behind:
hidden.Attributes.Add("oninit", "initHiddenConfigure("this");
I'm working on custom web control, inherited form label control. Try to run some JavaScript in page load event. But not working! Or any equivalent onload event for label control?
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I understand I need to load my dynmaic control on every postback and preferrably in Page_Init(). But my dyanmic controls are loaded from a dropdownlist selectedindexchanged event handler. Now after any postback, my dynamic controls are gone. How would I force it to load on every postback ?
View 2 RepliesI have a login.ascx control with three controls (LoginName, Password and btnLogin) , I want to rase a click event on this button from .aspx page because some restriction is there so that I am unable to write any code on .ascx page.I am bale to put loginName and password on .ascx by using query string but unale to raise event.
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We have a function that changes the iframe height at the window.onload event so we can adjust it to the page contents. The problem is that after clicking in an asp:menu the height its restored to its default and the window.onload event doesnt fire...so we need the event that would fire in subsequent loads (tried window.unload but didnt trigger)
The resize function cant be called on the asp:menu click because the window wouldnt have finished loading so the height calculation would fail...
I have the following download request in javascript:
var exportWindow = window.open('Download.ashx?source=1', '');
exportWindow.onload = function() {
alert('finished');
};
My problem is that the above alert box does not appear. The download.ashx sets up the following response (which will be saved as a csv file), which works fine.
context.Response.ClearContent();
context.Response.ContentType = "application/text";
context.Response.AddHeader("content-disposition", "attachment; filename="" + fileName + """);
context.Response.Write(resultWriter.ToString());
context.Response.Flush();
context.Response.Close();
If I replace the download.ashx with a normal aspx page, then the alert appears. So my question would be: is it possible to know programatically when the dowload.ashx returned with a response?(using FF3)
We are writing a portal and like every portal we store html data in Db fro Modules. So I thought that I can cache each module in files. I use OnLoad event to check if there is a cache file for this Module, use that and else create cache file:
if (!IsPostBack)
{
string Path = AppDomain.CurrentDomain.BaseDirectory + "CacheModules" + ModuleId + ".dat";
if (File.Exists(Path))
{
Controls.Clear();........
I put following on Page_onload event, I am not sure why it is not working. However when I use with dropdown, it is working fine.
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I want to call a javascript function at onload event of gridview..But I am getting Compilation error. How can I do this?
Basically I am using a javascript in .aspx page which have a master page. I want to get the value from javascript in code behind.
how to stop body onload= event from firing when user clicks server side button .
this is my below code in client side
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when i clicks server side button it raises body onload function again?
I want to raise this body onload function only when page load not in server side button click.
I'm trying to do something what I thought was simple: Attach a local click event to a DataList item. Yet I can't get it to work.
To make things simplest for everyone to understand I've created this sample little project.
I have a form in user control which submits data in database and clicking button. how to attach this button press even directly in the aspx page. I do not want to make delegate and want to use default event.
View 1 RepliesI'm trying to create ASP.NET buttons programmatically inside an update panel in my SharePoint instance, but because of the page life cycle, I can not attach server side events on buttons.
Here is the code;
TableCell tcellbutton = new TableCell();
b.Click += new EventHandler(b_Click);
b.CausesValidation = true;
tcellbutton.Controls.Add(b);
tr.Cells.Add(tcellbutton);
table.Rows.Add(tr);
panel1.Controls.Add(table);
void b_Click(object sender, EventArgs e)
{
string studentnumber = (sender as Button).ID.ToString().Substring(3, (sender as Button).ID.ToString().Length - 3);
TextBox t = panel1.FindControl("txt" + studentNumber) as TextBox;
}
I am adding a click event (display alert on click) to a html hyperlink inside an UpdatePanel on document(ready). However, the event never gets fired when I click the hyperlink. Is it because of ASync postback? What is the correct way to do this?
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