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Including a Handler Response inside a Web Form

I am generating HTML in the Page Load method in more than 1 page.
All those generated HTML are the same across all pages.
I found that it's a pain to have the same codes in every page because once I need to change something, I need to change them in all pages.
Example:
I have a div in each of those page:
<div id="Questions" runat="server"></div>
In the Page Load method of each page, I generate the same HTML.
Questions.InnerHTML = "<span>...etc...</span>";
So I decided to make a page that generates those contents, then load this page inside the div of the other pages, means, if I ever need to change, I only change this page.
I created a Handler, Questions.ashx. This handler generates that HTML and sends back a response.
Now to include it, I know I can use JQUERY's .load() function, but I would like to generate those HTML from server side.
What I've tried:
Questions.InnerHTML = LoadControl("~/Handlers/Questions.ashx").ToString();
But I received this error:
Type 'Questions' does not inherit from 'System.Web.UI.UserControl'.

"LoadControl" is for "User Controls", not HTTP Handlers..
You will probably be better off creating a User Control, which is an .ascx file. This can contain HTML, ASPX controls and code behind, and can be referenced by any ASPX page.
More Info here:
http://msdn.microsoft.com/en-us/library/y6wb1a0e(v=vs.100).aspx

How to pass values from an asp.net child page to the parent page

I have two web pages, Page1 and Page2, which can both open the same child popup page.
If the parent page is Page1 I want certain input from the Child page to returned to the parent page and if the parent page is Page2 I want other information to be returned.
I do identify who is the parent page and how do I return the input to it and have it show in the proper text box or DroDownList?
I tried using Request.UrlReferrer putting results in a string variable and I got an error 'object not set to an instance'.

As both the pages can be parent , write the a javascript function that works as receiver on both the page and write code in it as per your requirement.
e.g.
javascript on Parent page:
SetDataFromPopup(data)
{
document.getElementById('TextBox1ClientId').value = data;
}
On popup write the following line
window.opener.SetDataFromPopup(data);
this should be called on the event where you want to pass the data e.g. suppose you have a button on client click of it you want to pass the data , the code should look like:
<input id="btnSave" type="submit" onclick="window.opener.SetDataFromPopup(data);" >Save</input>

ASP.net Passing Links from Page to Page

I am trying to display a page into an IFrame.
The IFrame is displayed into a fancyBox overlay popup.
I have a list with the http links (gets compiled at runtime and it constantly changes).
Using a global variable I can access the list with the links.
But the http link in the list must match the link I have clicked.
If I can even get the link which I have clicked it will also be enough (the link brings up a fancyBox popup so it doesn't actually bring up a new page so to speak)
How to do that?

You have to write some tricky code to achieve this, main goal is to edit the dynamically added page content by adding wrapper tag (with onclick event) around all the links, writing javascript to be called using that wrapper to findout which link has been clicked,
You can try this by doing following steps
1) Get the content of IFrame , using the following JQuery code you can get the content of IFrame
var $currentIFrame = $('#myIFrame');
var content = $currentIFrame.contents();
2) Now manupulate these content by finding all the links inside that page and wrapping them with a tag that should have onclick event e.g. span , you have to write some javascript function to fire on a link if user clicks it.
see the following link for how to manipulate content
Get all links inside iframe and add blank target attribute

Allow .ASPX page to display before .ASCX control finishes loading?

I have an ASP.NET page with one control (.ascx) on it. The page (.aspx) onload assigns some text to a couple labels and passes a product ID to the .ascx control. The .ascx control, onload, takes that product ID from the .aspx page and hits the database several times, does several calculations, etc - basically takes a long time to load.
So when I'm clicking a link to this .aspx page, it is taking 7-10 seconds for the page to load. I've narrowed it down to the calculations on the .ascx control being the culprit and I've optimized the code as much as I can ... but it's still taking too long.
Is there a way to load the .aspx page BEFORE the control loads? (Maybe display a "Loading..." animation? Like used in an UpdateProgress?)

You could do this with an UpdatePanel. It will take a little trickery, but try something like this:
1) Put the UserControl in an UpdatePanel.
2) Put a public property on your usercontrol like IsEnabled that it will use to conditionally do nothing or render a "please wait." Set it false from your main page.
3) Add some code in OnInit to your main page:
if (MyScriptManager.IsInAsyncPostback) {
MyUserControl.IsEnabled=true;
}
4) Add a client script along these lines:
finished=false;
Sys.WebForms.PageRequestManager.pageLoaded(function(sender,args) {
if (!finished) {
finished=true;
__doPostBack('','');
// you can include the uniqueID of your updatepanel as the first arg
// otherwise it will refresh all update panels
}
});
or with jquery..
finished=false;
$(document).ready(function() {
if (!finished) {...
}
});
What this should do is cause an async postback to be initiated immediately after the page is done loading, which will in turn cause the update panel to be refreshed. Since you set it to be enabled when it's in an async postback, it will render itself the 2nd time.

The only possible way to achieve this is by setting it up as a separate HTTP resource. At the moment .NET is integrating the control into the page so that it is waiting unti it has everything it needs to respond.
You could do this a multitude of different ways:
Web Service that gets called via javascript
Seperate page which contains the control (and is hosted within an iFrame to appear to be on the same page)
The best way to do this would be to use an iFrame (or something similar) which will instruct the browser to request the control after the main page has been sent).

Personally, I would never use an iFrame to load content on a page - that's more like a hack than anything and plus, iframe == "bad".
But they are right, you won't be able to do anything like what you're looking for.
If the user control DOES NOT have any web controls that cause a postback (or have any form controls that you need to access during a postback), then I would use AJAX to request the data on the server after the page has already loaded and use javascript to display the content on the page.

passing value from opener to popup and processing it server side, not client side. Cant use a GET

I have an aspx web page (opener) which opens a popup window
In the popup window I need to retrieve the value of a hidden field which exists in the opener page.
So this is all straight forward using Javascript.
However, here’s the problem, I need the value of the hidden field to be processed SERVER side before the pop up page loads
(Basically, the hidden field contains XML which need to be deserialized server side and the data used to construct the DOM of the popup page)
So how do I pass the data in the hidden field of the opener, to get processed serverside in popup?
The data is Waaay too long to be passed as a GET. i.e. in the querystring of the popup page
What are the other options here?
Retrieve it using Javascript in popup, then do a postback to reload the page (very ugly)
Somehow post the data when opening the popup? Is this possible and can I stil pass other info via the querystring
Any other ideas?

Have a form like this
<form method="POST" action="action.php" onsubmit="open_popup(this);">
<input name="really-big-field" type="hidden">
</form>
also, javascript like this
function open_popup(form)
{
window.open('action.php', 'actionpopup','width=400,height=300');
form.target = 'actionpopup';
}
window.open() will open a popup like you want.
Setting the form's target to the opened popup will make sure that the form will POST to that popup.
Since a POST is made, you can send larger data than you can send using GET.
You can process the data server side in action.php (or in ASP.Net/VB file).

My usual solution to this sort of issue is to use XmlHTTPRequest to post the XML to the server, which simply stores the XML against some unique ID such as a GUID and have the ID returned from the server.
The URL you provide for your popup would then only need to carry this ID rather than the whole XML. Now when the server code on the other end of that URL needs the XML it can use the ID to look up the XML (probably deleting it from its temporary store at the same time) and can process the XML as if had been posted in the request.

Edit: Sorry, I realize this doesn't answer your question. I didn't read it clearly enough and didn't realize you needed to do it server side. I suppose if you wanted to take this path, though, you could then AJAX up your page to build it.
Parent page:
foo = 'bar';
child = open ("popup.html");
// you can now access the new windows functions with child.varname and child.function()
Child page:
alert(window.opener.foo);
Should alert Foo. Therefore you can:
somevar = window.opener.document.getElementById('id').value;
to get the field's value.