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How to find which control triggers the event inside a repeater

How to find which control event got triggered, for example, if there are 5 columns in the repeater if the 2nd checkbox or 3rd drop-down list causes the event. How to find which control event got triggered, so that the particular control related logic alone will be executed without disturbing other column controls.
The sample repeater code is attached as follows,
<asp:Repeater ID="rptTest" runat="server">
<ItemTemplate>
<td class="repeater-col">
<div>
<asp:TextBox ID="txt1" runat="server"></asp:TextBox>
</div>
<div>
<asp:DropDownList ID="ddl1" runat="server" OnSelectedIndexChanged="ddl1_SelectedIndexChanged" AutoPostBack="true">
</asp:DropDownList>
</div>
<div>
<asp:CheckBox ID="chk1" runat="server" OnCheckedChanged="chk1_CheckedChanged" AutoPostBack="true" />
</div>
</td>
</ItemTemplate>
</asp:Repeater>
There are lot more dependent controls presented inside the repeater. Based on the selection of the controls the data to the other controls are bound and processed. The logic bounded to the repeater will be handled on the respective events for example on chk1_CheckedChanged and ddl1_SelectedIndexChanged
Kindly help on this! Thanks in advance!

You can cast the sender back to the correct Control type. Then you can access it's properties. If you want to know which items the control was in, you can use the NamingContainer
protected void ddl1_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList drp = sender as DropDownList;
drp.BackColor = Color.Green;
RepeaterItem item = drp.NamingContainer as RepeaterItem;
int itemIndex = item.ItemIndex;
}

How to avoid post-back of Check Box inside repeater

I am newbie for asp.net,
I have a repeater which contains check box,whenever I check the check box I am firing an event on checkchanged,but the page postbacks.
I have an update panel for the entire content in my page,but still postback occurs.Is there anyway to avoid postback.
(Ps:To avoid Postback,I am meaning to avoid the flicker that occurs)
Thanks
<asp:Repeater ID="rptrDepartment" runat="server" OnItemCommand="rptrDepartment_ItemCommand"
OnItemDataBound="rptrdepartment_databound">
<ItemTemplate>
<tr>
<td>
<asp:CheckBox ID ="chkRow" runat="server" OnCheckedChanged="ChkRow_ChkChanged" AutoPostback="true" />
</td>
</tr>
</ItemTemplate>
</asp:Repeater>
And in my .cs page,
protected void ChkRow_ChkChanged(object sender, EventArgs e)
{
//some method
}

Just keep your repeater inside update panel rather than entire page, if you want some other controls also need partial postback then you can go for multiple update panels.

Value is not found in boundfield in gridview?

I am trying to assing value to hiddenfield on indexchange event of dropdownlist ! Actually the problem is when I am trying to update my record i can not find value of that hidden field ! Kindly give me solution or suggest any another option ! Thank You !
My grid view is
<asp:TemplateField HeaderText="LocCode" SortExpression="LocCode">
<EditItemTemplate>
<ajax:UpdatePanel ID="upEditsLocation" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DropDownList ID="ddlLocation" runat="server"
DataSourceID="sdsLocation"
OnDataBound="ddlLocation_DataBound"
DataValueField="LocCode" AppendDataBoundItems="false"
DataTextField="LocCode"
AutoPostBack="true"
onselectedindexchanged="ddlLocation_SelectedIndexChanged">
</asp:DropDownList>
<asp:SqlDataSource ID="sdsLocation" runat="server" ConnectionString="<%$ ConnectionStrings:ccConnString %>"
ProviderName="<%$ ConnectionStrings:CCConnString.ProviderName %>" SelectCommand="Select LocCode from Location">
</asp:SqlDataSource>
</ContentTemplate>
</ajax:UpdatePanel>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="lblLocation" runat="server" Text='<%# Bind("LocCode") %>'>
</asp:Label>
</ItemTemplate>
</asp:TemplateField>
and my indexchange event is
protected void ddlLocation_SelectedIndexChanged(object sender, EventArgs e)
{
hdloc.Value = ddlLocation.SelectedItem.Text;
}
And my hidden field is
<asp:HiddenField ID="hdloc" runat="server" />

From the code I can see the HiddenField is not part of your update panel. Hence if you assign any value to it, it will not reflect on client machine. Increase the scope of panel to include the hidden field, and then try.
OR you can try this solution from ASP.net Forum
Here is a small tutorial on update panel (MSDN)
Hope this helps you.

GridViewRow cancel = (GridViewRow)GridView1.Rows[e.RowIndex];
Label lbldeleteID = (Label)cancel.FindControl("lblid");

If you can't access hdloc from code behind, either is not added by Visual Studio on aspx.designer.cs (try delete it and add it back or change the id and then back to original value) or the hidden field is placed in other template of another binding control, which means you need to use ctrl.FindControl("hdloc") then cast to HiddenField.
Also you need to place this hidden field into an UpdatePanel with UpdateMode="Always".
protected void ddlLocation_SelectedIndexChanged(object sender, EventArgs e)
{
hdloc.Value = (sender as DropDownList).SelectedItem.Text;
}
I'm sure that ddlLocation.SelectedItem.Text, like you use it, it gives a compilation error, because ddlLocation is not visible on code behind, since is inside of EditItemTemplate.

DetailsView FindControl() returns null after some postbacks

I've been working for a long time with GridViews and DetailsViews, but yesterday I've come across a new scenario, which I quite do not understand.
I have a GridView with ImageButton (CommandName="Insert") which will change the mode of the DetailsView to Insert. Afterwards I'll look for a DropDownList inside that DetailsView and add some items dynamically. Works fine, but one first the first time I press that ImageButton. If I click on "Cancel" in the DetailsView and press the ImageButton again, the .FindControl() Method returns null. What life cycle problem am I facing here?
I've created this sample: (To make it run in your Visual Studio, just bind a DataSource to the DetailsView, otherwise it will not be rendered)
Markup:
<asp:GridView ID="gvCategory" runat="server" OnRowCommand="gvCategory_RowCommand">
<Columns>
</Columns>
<EmptyDataTemplate>
<asp:ImageButton ImageUrl="~/images/add.png" ID="ibAdd" runat="server" CommandName="Insert" />
</EmptyDataTemplate>
</asp:GridView>
<asp:DetailsView ID="dvCategory" runat="server" Width="150px" AutoGenerateRows="false"
AutoGenerateInsertButton="True" DataSourceID="LinqDataSource1">
<Fields>
<asp:TemplateField HeaderText="foo">
<InsertItemTemplate>
<asp:DropDownList ID="ddlCategory" runat="server" Width="150"></asp:DropDownList>
</InsertItemTemplate>
</asp:TemplateField>
</Fields>
</asp:DetailsView><asp:LinqDataSource ID="LinqDataSource1" runat="server"
ContextTypeName="WebApplication1.DataClasses1DataContext"
TableName="Categories"></asp:LinqDataSource>
Codebehind:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
this.gvCategory.DataBind();
}
}
protected void gvCategory_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "Insert")
{
this.dvCategory.ChangeMode(DetailsViewMode.Insert);
DropDownList _ddlCat = (DropDownList)this.dvCategory.FindControl("ddlCategory");
if (_ddlCat != null)
{
_ddlCat.Items.Clear();
_ddlCat.Items.Add(new ListItem() { Text = "-- empty --", Value = "-1" });
}
}
}
I have also tried using a ItemTemplate, and not a InsertItemTemplate, but this results in the same. After using the ChangeMode-Method the DetailsView.CurrentMode == InsertMode. The only thing I can think of is, that the markup is already generated for the ItemTemplate and changing the Mode to InsertMode can't affect the rendered markup, or something like this.
Does anybody have a solution to this? =)

I think you are on the right track. It's hard to tell without seeing all of the code, but basically any time you change the rendering mode of a row in a repeater-type control you need to rebind it so that it's re-rendered. The fact that FindControl is returning NULL means only one thing: THE CONTROL IS NOT THERE. Which means it was not rendered. You can verify this by looking at the control hierarchy.
So, in your handler for Cancel are you rebinding?

How Do I Get a Dynamic Control's Value after Postback?

I have a listview that adds controls in the ItemDataBound Event. When the postback occurs, I cannot find the new controls. After a bit of research, I found that ASP .NET needs these controls created every time, even after postback. From there I moved the function to bind the ListView outside of the if (!Page.IsPostBack) conditional. Now I get the dynamic controls values but the static controls I have are set to their defaults. Here is a sample of what I am trying to accomplish:
For brevity, I left some obvious things out of this example.
<asp:ListView runat="server" ID="MyList" OnItemDataBound="MyList_ItemDataBound">
<LayoutTemplate>
<asp:PlaceHolder runat="server" ID="itemPlaceholder" />
</LayoutTemplate>
<ItemTemplate>
<asp:PlaceHolder runat="server" ID="ProductPlaceHolder">
<asp:TextBox runat="server" ID="StaticField" Text="DefaultText" />
<asp:PlaceHolder ID="DynamicItems" runat="server" />
</asp:PlaceHolder>
</ItemTemplate>
</asp:ListView>
and here is the codebehind:
protected void MyList_ItemDataBound(object sender, System.Web.UI.WebControls.ListViewItemEventArgs e) {
PlaceHolder DynamicItems = (PlaceHolder)e.Item.FindControl("DynamicItems");
DynamicItems.Controls.Add(textbox);
}
So, like I said, if I only databind when Page != PostBack then I cant find my dynamic controls on postback. If I bind every time the page loads then my static fields get set to their default text.

Try moving the data binding of the ListView into the OnInit() event.

Very similar question (instead of populating a ListView the guy is generating a set of buttons). Briefly, you'll find that you have to store the items in the list in your Viestate - than fish it out on Postback and re-populate the list.
Note that this solutions implies dropping data-binding (which you might not wanna do for others reasons).
Hope it helps.