C# - Listbox Not Changing Index?
Sep 14, 2010
My question is probably a simple one to people used to ASP.NET, So here it is:
I have a webform in a master page that has a listbox which populates itself with numbers which serve as unique id for my objects.
The only problem is that the selected index property of the listbox is always -1 and it automatically deselects itself, no matter what I select. I understand that the index is -1 when you havent selected anyhting, but I have. Here is my C# code that I used to test it and my ASP.NET code:
[code]....
I use the first message box to see what the selected index is and the second to check my 3rd items in the listbox is being recognised.
[code]....
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May 2, 2010
I have some problem to understand how this example works with the updatepanel. I have put a ListBox4 and a label inside an updatepanel and put the property for the ListBox to AutoPostBack = true; So what I now am trying to do is when I click on the four items in the ListBox, I want the label to update the new String that is clicked in the ListBox. However what first happens when I click the 2:nd item is that I get the error:
Index was out of range. Must be non-negative and less than the size of the collection. I wonder what the correct way is to do this. I am not sure to know what is right here ? I think many example I do will be solved if I learn this one.
[Code]....
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Jun 29, 2011
I want to display whatever i select in the listbox into a label.
I thought it was as simple as this but nothing seems appear.
Protected Sub lbxInstalledPrograms_SelectionIndexChanged(By Val sender As _ Object, ByVal e As EventArgs) Handles _ lbxInstalledPrograms.SelectedIndexChanged
lblDisplayDetails.Text = lbxInstalledPrograms.SelectedItem.ToString()
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Feb 19, 2011
I have two ASP.NET ListBoxex in a usercontrol.
databinding event fires once. i am sure and i did trace.
but listbox always returns first value !
it is strange for me.
and i don't know how to fix it.
[code]....
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Jul 2, 2013
I have a set of values in a listbox on an ASP webform. I can select items, and in code, if the user selects some row from a different grid, the listbox shows the correct value. The user can also select a different value. All of this appears to work as I would expect. However, that's as far as it goes. At first, the SelectedIndexChanged event wasn't firing. I determined that was because I hadn't hooked up the event handler, which I did with this:
Code:
asp:ListBox ID="AgencyListBox" runat="server" OnSelectedIndexChanged="AgencyListBox_SelectedIndexChanged" EnableViewState = "true">
(the EnableViewState wasn't part of that solution. I added it later)
Now, the SelectedIndexChanged event fires, though it doesn't fire when the user selects something, it changes later, possibly in response to an AutoPostBack, since I read that will trigger the SelectedIndexChanged event. That's fine with me, either time will work ok. However, the SelectedIndex itself is always -1, as if nothing was ever selected. In fact, though I can see visually that something is selected, I have yet to figure out what that was, or how to access the index, the text, or anything even the fact that something was selected.
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Dec 5, 2013
I have a couple pages that are all pretty similar. Each of these pages consists of some number of views. Roughly speaking the first four views on each page are the same. The first page has a listbox and a textbox, then next several pages have listboxes. Because these views are the same between all the pages, and because the code behind them is the same, I built up the first page and got it working, then copied and pasted the information over for the other pages. The pages all differ in what the textbox does, but the listboxes are all identical in every way.
So, what I am seeing is that the original page works perfectly. When I go to any of the other pages, the behavior is bizarre. I was a bit surprised to find when the SelectedIndexChanged event was raised for the listbox, but it's fine. In the SelectedIndexChanged event, some minor stuff needs to happen as long as the selectedIndex is not -1. I am getting the SelectedIndexChanged event when it should happen. I see this by putting a breakpoint in the event handler. The SelectedIndex is ALWAYS -1. I can't get the SelectedIndex to be anything else, though it works in the original page from which the code was copied.
Naturally, I assumed that I had overlooked some change in the copying and pasting. That doesn't appear to be the case, but it still makes the most sense. The event is triggered by a change in the selectedIndex on the page that is currently loaded. However, the SelectedIndex hasn't changed because it was -1 and is still -1. The SelectedItem is still nothing, as it was before. There also isn't any problem that I can find with the copying and pasting. I even tried renaming two of the listboxes on one of the pages so that they would be truly distinct from the page that was working (different ID, which shouldn't matter since they are different fields). This had no impact. Nothing I can do will cause the SelectedIndex to be anything other than -1.
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Feb 8, 2010
I have up and down arrows next to a listbox and i need to switch the actual index of the item.
It is very similar to this thread: [URL]
But what actually I want is, if the listbox is like
item1
item2 (selected)
item3
So after clicking on down button it should display the listbox in following way
item1
item3
item2(selected)
The selected item should move downwards.
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Aug 5, 2010
I m new to MVC. Now i m need to integrate listview in my application, its done. but in that i need update paging. I searched some sites , but i didn't get well. i got some code as below
================================================================
<asp:ListView ID="UsersList" runat="server">
<LayoutTemplate>
<tr id="itemPlaceHolder" runat="server"> [code]...
It shows the paging well but page index changing is not work well. what is wrong in my coding? or missing any code? or need more?
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Oct 25, 2010
As you can see in the picture below i've got a Page control with inital letters which cotains a listbox showing different wood articles. When i click on a Tab, the selected tab page get's a new Listbox control with the wood articels starting with the selected initial letter.
Creating the listbox:
[Code]....
[Code]....
When i click on a item inside the listbox, following code will be executed:
[Code]....
So far, it works fine for me. But when i change the selected Tabpage, the first SelectedIndexChanged in the listbox in the new shown tabpage is not recordnized. That means i have to select a new item and click on Search = the selected Item is still the item i selected before i changed the tab. Then i select the item again and click on search the index changed is recordnized. So why do i have to click two times on search to get the new selected item after a tab page changed?
Here is the full code:
Searchpanel:
[Code]....
The WC_WoodList
[Code]....
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Jun 27, 2014
I have a SQL table used by a third party application that I have very little control over. The table contains a list of assemblies and their corresponding serial numbers. The tables primary key is a composite of the assembly number and serial number. There is no field I can use, reliably as an index.
I have an application I'm working on that pulls all the serial numbers from that table based on the assembly in a SQL View. I've then written code that pulls the serial numbers from that view based on the part number in a textbox on the form. That functionality works fine but I had both my datatextfield and datavaluefield set to the serial number. I've created another empty listbox that I would like to populate from a serial number or serial numbers being selected in the first. That is not working, I believe, because there is no index for the list.
My question is...How can I add an index value to each serial number as they populate from the SQL table. I've included the code below that I have pulling the serial number values.
This is an ASP.net VB webform.
Code:
Private Sub FillSnAvailList()
Dim strconnect1 As String = ("Data Source=MyDataSource")
Dim con1 As New SqlConnection(strconnect1)
con1.Open()
Dim cmd1 As New SqlCommand("SELECT [sPartNum], [SerialNum] FROM [V_MaxSerialNum] WHERE ([sPartNum] = @sPartNum)", con1)
[Code] ....
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Jun 7, 2010
i have a user control that includes a dropdown list its actually a page navigator when the user press next page iam setting the index of the selector to the value of a hidden textbox where textbox is filled from javascript function. ex txtbox initially is 1. then when next pressed it is 2 and so on but when doing postbacks i.e pressing next it is not changing the index although in the debuy its showing its setting to the new value. as if there is something that is reseting it to the initial value after the page loads if i put my method in the prerender method its working fine. but in the page_load method its not updating to the new index changed. i need to put it in the page_load method as i have to register some event handlers for the navigator.
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May 23, 2012
Client side
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" Â
ToolTip="M8 Media Educational Directory" GridLines="None" AllowPaging="True" Â
PageSize = "1" OnPageIndexChanging = "OnPaging" >
Server side
protected void OnPaging(object sender, GridViewPageEventArgs e)Â Â Â {Â Â Â Â Â Â Â
GridView1.PageIndex = e.NewPageIndex;Â Â Â Â Â Â Â
GridView1.DataBind();Â Â Â
}
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Mar 23, 2010
I have a listBox that is bounds its content from the database. This control is inside an itemTemplate. When the item template is boudned, I want to select the corresponding value.
I have this ugly single line of code:
[Code]....
What it does is to select the right value to a ListBox that is databinded with values inside a DetailsView
here is the rest of the code:
<asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="ID" DataSourceID="SqlDataSource4"
EnableModelValidation="True" ondatabound="DetailsView1_DataBound">
<Fields><asp:TemplateField><ItemTemplate>
<asp:ListBox ID="lbATechAuthCheck" runat="server" Width="100%" DataSourceID="SqlDataSource2" DataTextField="status" DataValueField="id"></asp:ListBox><asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:myConnectionString
%>"SelectCommand="SELECT * FROM [Status]"></asp:SqlDataSource>
</ItemTemplate></asp:TemplateField></Fields></asp:DetailsView>
Is there an easier way to achieve the same thing perhaps without any code behind?
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May 7, 2010
this is performance related question. i have gridview and i wrote gridview selected index changing event .In that event i am enable and disable one button out side the gridview..
it is working fine and fast in my local system ..the problem is ,if i upload my application in server ,it takes more time to perform action in gridview selected index changing.how to avoid that problem ?
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Jan 18, 2011
Referring to a C#, .net, System.Web.UI.WebControls.Lisbox which has a multiple select option true and needs to do a postback every time selected index changes.
Problem is, the [SelectedIndex / SelectedItem / SelectedValue] is always on the value of the 1st selected item. Clicking on the second item, third item, does not change the SelectedIndex, causing the listbox to reload and scroll to the highest selected item position.
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Jan 4, 2011
I must be doing something wrong, but this makes sense to me. I have a Listbox loaded with tons of items from a datasource. A user clicks one of these items it grabs the selectedindex (an integer) and stores it in a HiddenField (works fine).
Now when the page does a complete a refresh (after postback) I want the ListBox to go back to that selectedindex that is in the HiddenField. Problem is, it seems that after postback the HiddenField is empty? Then I thought about storing the value in an Integer variable in code, but that is simply coming up as a zero at all times.
Question 1: What is the best/simplest way to do this?
Question 2: How?
I am currently grabbing it on selectedindex change
[Code]....
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Mar 25, 2011
I have already stored value of author id in list item value while page loads. but when I change index of drop down list to view author information error is shown. I tried to debug using check points and it seems Sqlreader isn't reading database second time.
Incorrect syntax near '='..
Here is my code
[code].....
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Jun 4, 2010
I created my page with asp dropdown. On selected index changed I am seeing postback operation on dropdown. I couldn't avoid postback operation of asp dropdown with updatepanel also.
IS there a another way to avoid dropdownpostback operation.
[Code]....
</contenttemplate>
</asp:updatepanel>
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May 7, 2015
I have manually databinded my gridview , but problem is it won't show 2nd page index .... here's a chunk of code :
<asp:CheckBox ID="SARecords" OnCheckedChanged="SARecords_OnCheckedChanged" AutoPostBack="True" CssClass="tooltips" data-original-title="View all mapped phases." data-rel="tooltip" data-placement="top" runat="server"></asp:CheckBox>
<asp:UpdatePanel ID="ExistingMappedUpdatePanel" UpdateMode="Conditional" runat="server">
[CODE]....
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Sep 13, 2010
Why I am unable to setfocus to my list box if the index > 820
My list box contains 2000 items and the index is not able to set the focus if the index > 820
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Dec 27, 2010
I've a gridview control that has paging enabled. The control works completely fine in IE. However I was shocked to learn that the same page is not working on firefox i.e when I click on a page index the grid doesn't show selected page's data!
The page is posted back when I click a page index, I've checked it in debug mode as well. However the code for "Page Index Changing" is never fired!
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Mar 22, 2010
'm using a gridview with paging and sorting in asp.net (language = VB).The gridview shows all the artists in my database. I've added a searchbox above my gridview, so users can search for certain artists by name.The search option works. If I enter the name: John --> it shows the artists who have the name John.Now for the problem:If the user filtered the gridview (for eample searching for John) and switches to another page of the gridview, the gridview is again filled with all the artists instead of the artists that are named John.
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Feb 28, 2011
How to get the selected item from the listbox in the selected index changed event. I tried: Label1.Text = ListBox1.SelectedItem.Text; It is giving me object set to null reference.
foreach (ListItem item in ListBox1.Items)
{
if (item.Selected)
{
//lblResults.Text += item.Text + "
";
Label1.Text = item.Text;
}
}
No use, no value coming in to label.
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Apr 22, 2010
i have a situation, like this, there is a one data grid, which is empty, in that we can add the values, in that grid was paging enabled, so after the 10 record, remaining values ll be in the next page of the grid, so if i want to view that value, i should be use the paging option, here i m getting proble, becz, here i have use the code
" gvViewGoodsRecive.PageIndex = e.NewPageIndex;
gvViewGoodsRecive.DataBind(); "
but , this is not sutable for my method, becz here i m not getting value from data base, i just add the values without save in the database.
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Jan 30, 2011
i have the following code:
[Code]....
3 nested dropdownlists SELECTing from DB. So i select the brand, then i select the model and then i select the product and click on SEARCH button.
But when i select thebrand, and then the model, and if i want to change the brand, it does not reset the second and third dropdownlists.
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