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Asp.Net data attributes dynamically updated through JS/jQuery but the updated attributes aren't updated when retrieved through code behind

I have an aspx page of images that, when selected, a popup appears prompting for various information tid bits that I then store the information as data attributes on hidden labels through use of jQuery (i.e. data-id="####", data-difficulty="###", etc.). I acknowledge that this isn't the best way to do it necessarily but I've tried other things (see below) and nothing has worked yet.
I've been attempting, and to no avail, to retrieve the dynamically updated data attributes so the various items can be stored to my local ms sql database. The updating of the attributes works perfectly in that I can view the items being updated properly in Chrome's developer tools. Despite this when I try to pull the same attributes I can see as being updated I'm unable to retrieve the updated values in the code behind and keep getting back the initial values (generally an empty string "").
Here's the implementation on the aspx page:
<asp:Label runat="server" ID="lblSelection" data-id="" data-count="" data-price="" data-difficulty="" CssClass="selected-items" />
and here's the relevant method being called when the "Submit" button is clicked further down on the same page:
protected void SubmitClicked(object sender, EventArgs e)
{
var currentID = lblSelection.Attributes["data-id"];
var currentCount = lblSelection.Attributes["data-count"];
var currentPrice = lblSelection.Attributes["data-price"];
var currentDifficulty = lblSelection.Attributes["data-difficulty"];
if (currentID == null || currentID == "")
{
// stop and throw an informative message to the user
}else{
// keep processing ...
}
}
The trouble is that when I run the project in debug mode and inspect those elements (again, making sure that I can visually see that the attributes are actually updated in the developer tools) they're all the initial value of "". My only guess is that there's some kind of post back issue but I wouldn't think that would happen until my method had been called and fully processed. As a note, I'm populating the images onto the page and updating their attributes already through a sql call based on the id of the item:
<img runat="server" src="" data-id="12345" />
The initial loading all works perfectly so I can clearly set the properties from the code behind fine. For whatever reason though I am unable to pick up the updated attribute values in the code behind after the jQuery updates the label's attributes (following some clicking and whatnot). Any tips or thoughts on this would be greatly appreciated.

What you are trying to do cannot work because:
The value of custom attributes is not posted back to the server (as discussed here).
Even if you set the text of the Label in client code, it would also not be available in the Text property in code-behind. A Label is rendered as a span element in the page, and the content of that type of element is not posted back to the server.
A nice list of properties included in a postback is given in this topic: Which values browser collects as a postback data?
As suggested by mshsayem, you should use HiddenFields. If, for some reason, you want to do it differently, you could use hidden TextBoxes, set their value in client code, and retrieve it with the Text property in code-behind. In other words: HiddenFields are not the only controls for which a value set in client-code can be retrieved in code-behind (but they are the obvious choice if the control is not to be displayed).

Asp.net controls not updating after a postback

I'm writing code to read data from asp controls to update records in a database. I've been debugging the last day and I've tracked it back to something that I ought to have noticed before.
The code first populates the controls with the existing values from the database.
When I click SAVE, it should read the current values from the controls and save with those.
Unfortunately, what it's actually doing is using the values of the controls before a change was made to them. It's not seeing the change to the controls.
Here's a sample:
<asp:TextBox ID="OtherCourseName_5" runat="server"></asp:TextBox>
Here's the corresponding behind code in the btnSave_onClick() function:
int object_number=5;
string other_course_name_string
= "OtherCourseName_" + object_number.ToString().Trim();
TextBox ocn = utilities
.utils
.FindControlRecursive(this.Master, other_course_name_string) as TextBox;
I'm using the FindControlRecursive() I found somewhere on the web. It works, I'm sure, but just in case, I tried to address the control directly as OtherCourseName_5.Text.
Even if I just display the value in OtherCourseName_5.Text, it gives the original value.
I use this same page for both entering new data and for editing data. It works fine when I enter the data. That is, it correctly sees that the TextBox control has changed from empty to having data. It's only when I invoke the edit function on the page (by passing edit=true). I invoke it this way by adding the switch edit=true as a query string (the program correctly reads that switch, gets to the appropriate area of code, prints out all the correct values for everything - except the contents of the controls!).
The page is far too complicated to post the entire thing. I've tried to convey the essential details. It's entirely possible that I've made a simple coding error, but it's seeming more a possibility that I fundamentally misunderstand how pages are processed.
Is there anything known that can make it seem as though the value of a control has not been changed?
Note 1: I thought perhaps I had to go to another field after I entered the data, but I tried that and it's still a problem.
Note 2: I'm using both TextBox and DropDownList controls and have the same problem with both.
Note 3: These controls are on a panel and the page is using a SiteMaster. I haven't had any problem with that and don't think the problem is there, but I'm down to questioning the laws of the physics at this point.

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
//populate controls with data from database
}
}
When you do a postback before the postback handler is evaluated the PageLoad event is raised
so if you don't avoid to rebind your control they will be loaded with the values from the database. And then the postback event will save them to db
Asp.net Page Lifecycle
(source: microsoft.com)

Submit a form from code behind

I'm having trouble implementing a functionality on my c#/asp.net app.
I have a form with a RadioButtonList and a submit button.
The RadioButtonList is generated on Page_Load() from a list of objects I retrieve from the database.
I would like to automatically submit the form if there is only 1 object in the list.
I have access to my Form object, to the submit button etc... but I can't seem to find a solution (in the end I'm looking for a kind of form.Submit() ) method.
Does anyone have an idea of how I could do this ?
Thanks in advance !
EDIT >> Here is the code :
.aspx : http://pastebin.com/0E6T7dqH
.aspx.cs : http://pastebin.com/54payZJP
EDIT2 >>>
As it seems there is no way to do what I wanted to do at first, I ended up using a session variable with a response.redirect()
Source :
http://dotnetslackers.com/Community/blogs/haissam/archive/2007/11/26/ways-to-pass-data-between-webforms.aspx

Post happens in the client side. As in Page_Load you are currently executing in the server side, just call the code you want to execute on post.
Edit: For actually going to another aspx
public void Page_Load(object sender, EventArgs e) {
if(!IsPostback && OnlyOneItem) {
Server.Transfer("TheOtherPage.aspx");
}
}
Server.Transfer will maintain the entire request, so your post data will be available.
http://msdn.microsoft.com/en-us/library/system.web.httpserverutility.transfer.aspx

Try something like this
In your Page_Load
if(!IsPostBack)
{
if(check for only one object)
{
//your submit code
}
}

I actually had to do something similar, once. Here is a way you can do it.
Asp.Net buttons have a property called PostBackUrl, and it does exactly what you would expect - it controls where the form will post if you click the button.
You can also use the RegisterStartupScript function to render javascript on the page.
Now, with these two pieces, you can achieve your goal.
if(!IsPostBack)
{
if(results == 1)
{
button.PostBackUrl = "next page's url"
//Register script to click the button using RegisterStartupScript
}
}
Now, having shown you this, I will warn you it may not make for the best user experience. When I did it, it was for a very specific case that had no other solution. The page will actually post back to the user, and they will see the page for a moment before the javascript to click the button takes effect. Additionally, when you set a button's PostBackUrl, that means that when it is clicked, your entire form will be posted to the page specified. The code behind for the current page will not fire at all, so if you have any validation, it won't run.
There's nothing wrong with letting the user click the button to submit the form even if they only have one choice. In my experience, users like to feel like they are in control on the system; they don't like it when pages just do things without their input.
Also, there is not really anything wrong with putting the information the next page needs into the session or even a database table, and using Response.Redirect. It's a fairly common practice and works reliably in most scenarios.

ASP.NET Ajax - Buttons 'postbacking' but functionality not happening

Here's the thing
I added a button to a webpart which saves some fields to MS-Excel.
var btn = new Button { Text = title, CssClass = css };
btn.Click += (sender,args)=>action();
Container.Controls.Add(btn);
This code is located inside OnInit() method in the WebPart. actionis the Action which does stuff, in this case:
Something.FillExcel(MyData);
Something.SaveExcel();
So what happens is, I click the button, it acts like doing the usual partial postback, and does absolutely nothing. I thought it could be something in the Fill/Save code, then I tried forcing an error just to see if it gets there. It seems the click event never fires, or, if it does, it doesn't run my code (?).
Here's the html, just in case:
<input type="submit" name="ctl00$m$g_b4af4370_c016_4712_9d60_fc8ca077a068$ctl359" value="Enviar Formulário" onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$m$g_b4af4370_c016_4712_9d60_fc8ca077a068$ctl359", "", true, "", "", false, false))" class="button" />
What could be happening?
Thanks in advance!
EDIT: After Cos Callis answered, I put my code inside OnLoad() instead of OnInit(). Here's new code:
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
var btn = new Button { Text = title, CssClass = css };
btn.Click += new EventHandler((sender,args)=>{
if (myform.Page.IsPostBack)
{
excel.FillExcel(); excel.SaveFile();
}
});
container.Controls.Add(btn);
}
I'm now getting a javascript error: SCRIPT5022: Sys.WebForms.PageRequestManagerServerErrorException: The given key was not present in the dictionary.

Because you are attempting to act on the INIT rather than the load, the data has not yet been attached at the server.
You should find this review of the life cycle of a web request in ASP.NET useful:
http://msdn.microsoft.com/en-us/library/ms178472.aspx.
Here is the relevant extract:
Initialization
During page initialization, controls
on the page are available and each
control's UniqueID property is set. A
master page and themes are also
applied to the page if applicable. If
the current request is a postback, the
postback data has not yet been loaded
and control property values have not
been restored to the values from view
state.
Load
During load, if the current request is
a postback, control properties are
loaded with information recovered from
view state and control state.
During initialization the control "exists" but has not yet been loaded with data from the postback. If you you move your code to "OnLoad" you should achieve the disired results. (Don't forget to wrap that in "if(IsPostback)")
Cheers,
CEC
//added resource: After posting my answer I thought you might find this article useful as well:
http://encosia.com/2007/10/24/are-you-making-these-3-common-aspnet-ajax-mistakes/

Sorry guys found out it was an error inside FillExcel(). I thought I would get that asp yellow page but instead it gives me a script error.
Maybe another common mistake for ajax/jquery/sharepoint newbies.
I'm accepting Cos Callis' reply as answer because he did answer everything I asked.

C# .Net variable unexpected re-initialation

So I am experiencing an issue with an .aspx page and some server side code, where I am getting unexpected results.
The goal of this page is simple, there are 5 radio buttons and a button with a server side onclick function. The idea is the user picks 1 of the 5 radio buttons, and then clicks the button. Upon clicking the button I verify (not using form validation, because I wanted a different feel) that a button is checked, and then store the selected option in a database.
Due to the fact that the number of radio buttons may change in the future I decided to try and abstract the number of radio buttons to make it easier on my self to change in the future.
So at the top of my server side code I created a list of possible options.
I then have a registerVote function that takes in a RadioButton object, and a number to grab a setting from the config file. I throw those 2 values into a wrapper class, and then add them to the list of possible options.
Finally when the submit button is pressed, I iterate through all possible options to see which one is checked, and grab its associated value.
public partial class VotePanel : System.Web.UI.Page
{
List<VoteOption> voteOptions = new List<VoteOption>();
public string registerVote(RadioButton newRadioButton, int voteOption)
{
voteOptions.Add(new VoteOption(newRadioButton, voteOption));
return ConfigurationManager.AppSettings["vote_option_" + voteOption];
}
protected void Submit_Click(object sender, EventArgs e)
{
//Check vote
string vote_value = "";
bool someButtonChecked = false;
foreach (VoteOption vo in voteOptions)
{
if (!someButtonChecked && vo.button.Checked)
{
vote_value = vo.movie;
someButtonChecked = true;
}
}
//....
}
}
class VoteOption
{
public RadioButton button;
public int vote_value;
public VoteOption(RadioButton r, int v)
{
button = r;
vote_value= v;
}
}
The code I use in page to add a radio button looks like this
<asp:RadioButton ID="RadioButton1" runat="server" GroupName="Vote" style="position: relative; top: 3px;" /><%=registerMovie(RadioButton1,1)%>
Now for the problem I am experiencing. Whenever the submit button is clicked, the list has a count of zero, and looks like it has been reinitialized. I validated that values are being added, by returning the list count in the registerVote method, and objects are indeed being added, but for some reason are not available to the Submit function.
Now variables on a page like this shouldn't reinitialize right? I also tested a string, and it did not reset and was available to the Submit button. What I did was define a class variable string time = DateTime.Now.Ticks.toString(); and displayed that after the submit button was clicked, and the time was always the same reguardless of how many times I clicked it.
So why would my List reinitialize, but not a string? Any ideas?

Keep in mind that your page class will be constructed and destructed for every request - no state will be maintained between each page load, it is up to you to properly recreate state as needed. In this case it appears that your list voteOptions is not being recreated before Submit_Click is called.
You'll have to register all your voting options regardless of whether the page is in a postback or not inside the Page_Load or OnInit handlers of the page. This will reconstruct voteOptions, which will then be accessed when Submit_Click is called.
Take a look at the ASP.NET Page Life Cycle.

The problem seems to be that you are constructing the List<VoteOption> voteOptions at page render then expecting it to still be there on postback. The Page object does not exist past the point that the page is delivered to the browser, so your list of vote options gets disposed of as well when the browser has received the page.
You'll either need to reconstruct the voteOption list before or during Submit_Click on postback, or give yourself enough information in the value of the radio button that you don't need it.

I don't see in your code any place where the list that you are building is placed in memory. I believe you are rebuilding it on each page reload. P.s. might be my reading but you created a function called registerVote and you are calling a method called registerMovie so that might be your problem.
You could place the list in the session and get it back from session.
Personnally I would change the code to
1) Check if the list is in memory and get it. If not in memory call a method to generate it once and then place it in memory.
2) Use a RadioButtonList on your page that you can then bind to your list as a data source.

asp.net is stateless, so every postback (such as clicking Submit) recreates the server-side class. If you want your list to persist between calls, you should save it in ViewState or a Hidden field. Not sure about the string though; what you're describing doesn't fit the asp.net lifecycle.