Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

ASP.Net/C# - How to get value of a regular HTML Select List Box in code behind?

Posted on 2008-06-25
8
Medium Priority
?
4,087 Views
Last Modified: 2012-08-14
Hello all I could really use some help here.  I have a ASPX page that has a regular select list on it where the user can add and remove items via javascript.  I need to in my code behind on a save loop through each value that was entered into that select list to create a semi-colon seperated string.  Then the same coming back into the page I need to parse through the values and add to the list box.  I know how to handle the for loop for the coming back with a string split.  I just need to know how to add the item to the select list HTML.  Any help would be much appreciated.  Attached is the code from the page.
<script type="text/javascript" language="javascript">
	function remove()
	{
		var list = window.document.getElementById('myList');
		var keepLooking = true;
		while ( keepLooking ) {
			list.remove( list.options.selectedIndex );
			if ( list.options.selectedIndex < 0 ) {
				keepLooking = false;
			}
		}
	}
	
	function add()
	{
		var list = window.document.getElementById('myList');
		var tbox = document.getElementById('myText');
		var tval = tbox.value;
        var newOpt = document.createElement('option');
        var txt = document.createTextNode(tval);
        newOpt.appendChild(txt);
        newOpt.setAttribute('value', tval);
        //newOpt.text = tval;
        //newOpt.value = tval;
        list.appendChild(newOpt);
	}
</script>
 
<select id="myList" name="myList" size="10" style="width:200px;"></select>
<a href="javascript:remove();">Remove</a><br />
<input type="text" id="myText" value="" style="width:200px;"/>
<a href="javascript:add();">Add</a>

Open in new window

0
Comment
Question by:sbornstein2
  • 4
  • 3
8 Comments
 
LVL 21

Accepted Solution

by:
naspinski earned 1000 total points
ID: 21864804
Instead, why don't you make this an asp:dropdownlist and change the javascript to accommodate the newly generated IDs (view source).  Ass the asp controls just make an html drop list anyways, jsut takes care of a lot of the footwork of getting it to the backend.
0
 

Author Comment

by:sbornstein2
ID: 21864937
ya that is what I was thinking but im not sure how to do that.  Do I use just the name of the listbox? and also the other problem is I just need to make sure it does not post back.
0
 
LVL 21

Expert Comment

by:naspinski
ID: 21864975
If it does not postback, there is no way to get the codebehind (c#) the value, as that is server side.

So you need a postback... you could use an ajax asp:updatepanel for an asynch postback.

Also, to get the asp-made ids, just run your page, go into your browser and view source.  Then find the dropdowns and you can see the ID that asp made for them... use those.
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 

Author Comment

by:sbornstein2
ID: 21865002
ok so ya this would work and then I can use:

StringBuilder sb = new StringBuilder();
            foreach (ListItem item in lstBulletPoints.Items)
            {
                try
                {
                    sb.Append(item.Text.ToString() + ";");
                }
                catch (Exception)
                {
                    // ignore
                }
            }
that will create my list.

Can that ID ever change though and is there a better way to use like a client id or something
0
 
LVL 21

Expert Comment

by:naspinski
ID: 21865033
The ID will never change.  It is a bit of a pain, but in order to allow both server and client-side scripts to work on the same objects, you have to coax them into working sometimes.
0
 
LVL 39

Assisted Solution

by:Pratima Pharande
Pratima Pharande earned 1000 total points
ID: 21865043
<select id="myList" name="myList" size="10" style="width:200px;" runat="server"></select>

To add values thorugh asp.net

  myList.Items.Add("3");
                    myList.Items.Add("4");
0
 
LVL 21

Expert Comment

by:naspinski
ID: 21865074
wow... i feel like an idiot since I didn't even think of making it a server control :P  good call pratima

Just have to make sure it is inside of a form tag that is also runat="server"
0
 

Author Closing Comment

by:sbornstein2
ID: 31470523
both were helpful thanks guys.  I might use AJAX and a server control instead but nevertheless thanks for the help and awesome info
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In .NET 2.0, Microsoft introduced the Web Site.  This was the default way to create a web Project in Visual Studio 2005.  In Visual Studio 2008, the Web Application has been restored as the default web Project in Visual Studio/.NET 3.x The Web Si…
It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
Want to learn how to record your desktop screen without having to use an outside camera. Click on this video and learn how to use the cool google extension called "Screencastify"! Step 1: Open a new google tab Step 2: Go to the left hand upper corn…
Please read the paragraph below before following the instructions in the video — there are important caveats in the paragraph that I did not mention in the video. If your PaperPort 12 or PaperPort 14 is failing to start, or crashing, or hanging, …
Suggested Courses

972 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question