Introduction

Populating Data Controls

I have defined a class level (member variable) DataTable and using it to populate all Data controls. This DataTable has two column, ID and Description.

/// <summary>
/// Fill data into DataTable, DataSource for this demo
/// </summary>
private void FillDataIntoDataSource()
{
dTable.Columns.Add(new DataColumn("ID", typeof(int)));
dTable.Columns.Add(new DataColumn("Description", typeof(string)));
for (int i = 1; i <= 10; i++)
{
i++;
dTable.Rows.Add(i, "Record Number " + i);
}
}

<asp:GridView ID="GridView1" runat="server" AutoGenerateSelectButton="true" DataKeyNames="ID"
OnSelectedIndexChanging="GridViewGetSelectingValue">
</asp:GridView>

protected void GridViewGetSelectingValue(object sender, GridViewSelectEventArgs e)
{
string id = GridView1.DataKeys[e.NewSelectedIndex].Value.ToString();
lblMessage.Text = "GridView Selected ID : " + id;
}

<asp:DataList ID="DataList1" runat="server" DataKeyField="ID" 
onselectedindexchanged="DataList1_SelectedIndexChanged">
<HeaderTemplate><table border="1"></HeaderTemplate>
 
<ItemTemplate>
<tr><td><%# Eval("ID") %></td><td><%# Eval("Description") %></td>
<td><asp:LinkButton ID="lnkSelect" runat="server" CommandName="Select" Text="Select" /></td>
</tr>
</ItemTemplate>
 
<FooterTemplate>
</table>
</FooterTemplate>
</asp:DataList>

protected void DataList1_SelectedIndexChanged(object sender, EventArgs e)
{
string id = DataList1.DataKeys[DataList1.SelectedIndex].ToString();
lblMessage.Text = "DataList Selected ID : " + id;
}

Getting Selected Key Value from FormView Control

Hardly, you need to gethe selected record key value for FormView however, if you need to get the selected key value from FormView, you can use following approach.

<asp:FormView ID="FormView1" runat="server" DataKeyNames="ID" AllowPaging="true" 
OnItemCommand="FormViewGetSelectedID" OnPageIndexChanging="FormViewChangePage" > 
<HeaderTemplate><table border="1"></HeaderTemplate>
 
<ItemTemplate>
<tr><td><%# Eval("ID") %></td>
<td><%# Eval("Description") %></td>
<td><asp:LinkButton ID="lnkSelect" runat="server" CommandName="Select" Text="Select" /></td>
</tr>
</ItemTemplate>
 
<FooterTemplate>
</table>
</FooterTemplate>
</asp:FormView>

Specify DataKeyNames property as ID. As there is no event like SelectedIndexChange for the FormView so use OnItemCommand event to do that.  To fire OnItemCommand, I have placed a LinkButton and set its CommandName to Select and specified OnItemCommand event as FormViewGetSelectedID.

protected void FormViewGetSelectedID(object sender, FormViewCommandEventArgs e)
{
if (e.CommandName.Equals("Select"))
{
string id = FormView1.SelectedValue.ToString();
lblMessage.Text = "FormView Selected ID : " + id;
}
}

As this event whenever any command button will be clicked on FormView, so check for the command name. To get the selected value from the FormView, simply use the SelectedValue property of the FormView control.

Getting Selected Key Value from ListView

<asp:ListView ID="ListView1" runat="server" DataKeyNames="ID" 
onselectedindexchanging="ListView1_SelectedIndexChanging">
<LayoutTemplate>
<table border="1">
<tr><th>ID</th><th>Description</th><th>Select</th></tr>
<asp:Panel ID="ItemPlaceHolder" runat="server"></asp:Panel>
</table>
</LayoutTemplate>
 
<ItemTemplate>
<tr><td><%# Eval("ID") %></td><td><%# Eval("Description") %></td>
<td><asp:LinkButton ID="lnkSelect" runat="server" CommandName="Select" Text="Select" /></td>
</tr>
</ItemTemplate>
 
</asp:ListView>

I have dragged a ListView control from the ToolBox and specified LayoutTemplate and ItemTemplate. I have also specified DataKeyNames property as ID. To fire OnselectedIndexChanging event, I have placed a LinkButton and set its CommandName as select.

protected void ListView1_SelectedIndexChanging(object sender, ListViewSelectEventArgs e)
{
string id = ListView1.DataKeys[e.NewSelectedIndex].Value.ToString();
lblMessage.Text = "ListView Selected ID : " + id;
}
 

To get the selected key value from the ListView, use DataKeys property and pass NewSelectedIndex of the ListViewSelectEventArgs.

Getting Selected Key Value from DetailsView

Same as FormView, you may not need this so oftenly but you get the Selected key value like this.

<asp:DetailsView ID="DetailsView1" runat="server" Height="50px" Width="125px" DataKeyNames="ID"
OnPageIndexChanging="DetailsViewChangePage" OnItemCommand="DetailsViewGetSelectedID" 
AutoGenerateRows="false" AllowPaging="true">
 
<Fields>
<asp:BoundField DataField="ID" HeaderText="ID" />
<asp:BoundField DataField="Description" HeaderText="Description" />
 
<asp:TemplateField HeaderText="Select"><ItemTemplate>
<asp:LinkButton ID="lnkSelect" runat="server" CommandName="Select" Text="Select" /> 
</ItemTemplate></asp:TemplateField>
</Fields>
 
</asp:DetailsView>

I have specified DataKeyNames property as ID. As there is no event like OnSelectIndexChange so I have used OnItemCommand event to do that. To fire OnItemCommand event of the DetailsView, I have placed a link button and specified CommandName as select.

protected void DetailsViewGetSelectedID(object sender, DetailsViewCommandEventArgs e)
{
if (e.CommandName.Equals("Select"))
{
string id = DetailsView1.SelectedValue.ToString();
lblMessage.Text = "DetailsView Selected ID : " + id;
}
}

As this event will fire whenever any command button will be clicked, so first check it if the clicked button is Select. To get the selected key value use SelectedValue property of the DetailsView.

Getting Selected Value from Repeater Control

<asp:Repeater ID="Repeater1" runat="server" OnItemCommand="RepeaterGetSelectedID">
<HeaderTemplate><table border="1"></HeaderTemplate>
<ItemTemplate>
<tr><td>
<asp:HiddenField ID="HiddenID" runat="server" Value='<%# Eval("ID") %>' />
<%# Eval("ID") %> 
</td><td><%# Eval("Description") %></td>
<td><asp:LinkButton ID="lnkSelect" runat="server" CommandName="Select" Text="Select" /></td>
</tr>
</ItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>

As there is no property called DataKeyNames in the Repeater control as in case of all other data controls, so I have placed a hidden control and set its value property as ID, I will use this control to get the ID in the code file. There is no event like OnSelectedIndexChange so I will use OnItemCommand event to do that. To fire the OnItemCommand event, I have placed a link button and specified CommandName as Select.

protected void RepeaterGetSelectedID(object source, RepeaterCommandEventArgs e)
{
if (e.CommandName.Equals("Select"))
{
HiddenField hiddenID = (HiddenField) e.Item.FindControl("HiddenID");
string id = hiddenID.Value;
lblMessage.Text = "Repeater Selected ID : " + id;
}
}

As this event will fire whenever any button (if any other available) will be clicked on the Repeater control, so first check if the CommandName of the clicked button is Select. If it is, then find the HiddenField control and get its value.

Conclusion

In this article, I tried to show how to get the selected record key value from almost all Data controls available in ASP.NET. Please note that different events of these data controls may have differnt way to get it.

Hope this helps, feel free to download the sample. Thanks for reading.