RadComboBox in RadGrid
The Combo in Grid online example demonstrates how to load the ComboBox Items on demand in the RadGrid edit form. Two options are available to preselect a value in a RadComboBox when nested in a RadGrid EditTemplate:
If you populate RadComboBox with data using ASP.NET 2.0 or 3.5 DataSource types, you can set the SelectedValue like SelectedValue='<%#Bind("CompanyName") %>'
When you use Load On Demand or Automatic Load On Demand - you can add the previously selected Item by in the RadGrid OnItemDataBound event when in Edit Mode.
When you delete the text initially displayed in the RadComboBox - Load-On-Demand will fire and will populate the control with Items.
Below are the code snippets from the demo referred above:
<telerik:RadGrid RenderMode="Lightweight" ID="RadGrid1" GridLines="None" AutoGenerateColumns="false" PageSize="10"
AllowPaging="true" AllowSorting="true" runat="server" OnItemDataBound="OnItemDataBoundHandler"
DataSourceID="ProductsDataSource" AllowAutomaticUpdates="true" AllowAutomaticInserts="True"
ShowStatusBar="true">
<MasterTableView ShowFooter="false" DataKeyNames="ProductID" EditMode="InPlace" CommandItemDisplay="TopAndBottom">
<Columns>
<telerik:GridBoundColumn DataField="ProductName" HeaderText="ProductName" HeaderStyle-Width="300px"
ItemStyle-Width="300px">
</telerik:GridBoundColumn>
<telerik:GridTemplateColumn UniqueName="Supplier" HeaderText="Supplier" SortExpression="CompanyName"
ItemStyle-Width="400px">
<FooterTemplate>
Template footer</FooterTemplate>
<FooterStyle VerticalAlign="Middle" HorizontalAlign="Center" />
<ItemTemplate>
<%#DataBinder.Eval(Container.DataItem, "CompanyName")%>
</ItemTemplate>
<EditItemTemplate>
<telerik:RadComboBox RenderMode="Lightweight" runat="server" ID="RadComboBox1" EnableLoadOnDemand="True" DataTextField="CompanyName"
OnItemsRequested="RadComboBox1_ItemsRequested" DataValueField="SupplierID" AutoPostBack="true"
HighlightTemplatedItems="true" Height="140px" Width="220px" DropDownWidth="420px"
OnSelectedIndexChanged="OnSelectedIndexChangedHandler">
<HeaderTemplate>
<ul>
<li class="col1">Company</li>
<li class="col2">ContactName</li>
</ul>
</HeaderTemplate>
<ItemTemplate>
<ul>
<li class="col1">
<%# DataBinder.Eval(Container, "Text")%>
</li>
<li class="col2">
<%# DataBinder.Eval(Container, "Attributes['ContactName']")%></li>
</ul>
</ItemTemplate>
</telerik:RadComboBox>
</EditItemTemplate>
</telerik:GridTemplateColumn>
<telerik:GridTemplateColumn HeaderText="Category" ItemStyle-Width="240px">
<ItemTemplate>
<%#DataBinder.Eval(Container.DataItem, "CategoryName")%>
</ItemTemplate>
<EditItemTemplate>
<telerik:RadComboBox RenderMode="Lightweight" runat="server" ID="RadComboBox2" DataTextField="CategoryName"
DataValueField="CategoryID" DataSourceID="CategoriesDataSource" SelectedValue='<%#Bind("CategoryID") %>'>
</telerik:RadComboBox>
</EditItemTemplate>
</telerik:GridTemplateColumn>
<telerik:GridEditCommandColumn FooterText="EditCommand footer" UniqueName="EditCommandColumn"
HeaderText="Edit" HeaderStyle-Width="100px" UpdateText="Update">
</telerik:GridEditCommandColumn>
</Columns>
</MasterTableView>
</telerik:RadGrid>
<asp:SqlDataSource ID="ProductsDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString35 %>"
SelectCommand="SELECT products.[ProductID], products.[ProductName], products.[SupplierID], products.[CategoryID], suppliers.[CompanyName], suppliers.[ContactName], categories.[CategoryName] FROM [Products] AS products INNER JOIN Suppliers AS suppliers ON products.SupplierID = suppliers.SupplierID INNER JOIN Categories AS categories ON products.CategoryID = categories.CategoryID"
InsertCommand="INSERT INTO [Products] ([ProductName], [SupplierID], [CategoryID]) VALUES (@ProductName, @SupplierID, @CategoryID)"
UpdateCommand="UPDATE [Products] SET [ProductName] = @ProductName, [SupplierID] = @SupplierID, [CategoryID] = @CategoryID WHERE [ProductID] = @ProductID">
<InsertParameters>
<asp:Parameter Name="ProductName" Type="String" />
<asp:SessionParameter SessionField="SupplierID" Name="SupplierID" Type="Int32" />
<asp:Parameter Name="CategoryID" Type="Int32" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="ProductID" Type="Int32" />
<asp:Parameter Name="ProductName" Type="String" />
<asp:SessionParameter SessionField="SupplierID" Name="SupplierID" Type="Int32" />
<asp:Parameter Name="CategoryID" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
<asp:SqlDataSource ID="CategoriesDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString35 %>"
SelectCommand="SELECT [CategoryID], [CategoryName] FROM [Categories]"></asp:SqlDataSource>
protected void OnItemDataBoundHandler(object sender, GridItemEventArgs e)
{
if (e.Item.IsInEditMode)
{
GridEditableItem item = (GridEditableItem)e.Item;
if (!(e.Item is IGridInsertItem))
{
RadComboBox combo = (RadComboBox)item.FindControl("RadComboBox1");
RadComboBoxItem selectedItem = new RadComboBoxItem();
selectedItem.Text = ((DataRowView)e.Item.DataItem)["CompanyName"].ToString();
selectedItem.Value = ((DataRowView)e.Item.DataItem)["SupplierID"].ToString();
selectedItem.Attributes.Add("ContactName", ((DataRowView)e.Item.DataItem)["ContactName"].ToString());
combo.Items.Add(selectedItem);
selectedItem.DataBind();
Session["SupplierID"] = selectedItem.Value;
}
}
}
protected void RadComboBox1_ItemsRequested(object sender, RadComboBoxItemsRequestedEventArgs e)
{
string sql = "SELECT [SupplierID], [CompanyName], [ContactName], [City] FROM [Suppliers] WHERE CompanyName LIKE @CompanyName + '%'";
SqlDataAdapter adapter = new SqlDataAdapter(sql, ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString);
adapter.SelectCommand.Parameters.AddWithValue("@CompanyName", e.Text);
DataTable dt = new DataTable();
adapter.Fill(dt);
RadComboBox comboBox = (RadComboBox)sender; // Clear the default Item that has been re-created from ViewState at this point. comboBox.Items.Clear();
foreach (DataRow row in dt.Rows)
{
RadComboBoxItem item = new RadComboBoxItem();
item.Text = row["CompanyName"].ToString();
item.Value = row["SupplierID"].ToString();
item.Attributes.Add("ContactName", row["ContactName"].ToString());
comboBox.Items.Add(item);
item.DataBind();
}
}
protected void OnSelectedIndexChangedHandler(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
{
Session["SupplierID"] = e.Value;
}
Protected Sub OnItemDataBoundHandler(ByVal sender As Object, ByVal e As GridItemEventArgs)
If e.Item.IsInEditMode Then
Dim item As GridEditableItem = DirectCast(e.Item, GridEditableItem)
If Not (TypeOf e.Item Is IGridInsertItem) Then
Dim combo As RadComboBox = DirectCast(item.FindControl("RadComboBox1"), RadComboBox)
Dim selectedItem As New RadComboBoxItem()
selectedItem.Text = DirectCast(e.Item.DataItem, DataRowView)("CompanyName").ToString()
selectedItem.Value = DirectCast(e.Item.DataItem, DataRowView)("SupplierID").ToString()
selectedItem.Attributes.Add("ContactName", DirectCast(e.Item.DataItem, DataRowView)("ContactName").ToString())
combo.Items.Add(selectedItem)
selectedItem.DataBind()
Session("SupplierID") = selectedItem.Value
End If
End If
End Sub
Protected Sub RadComboBox1_ItemsRequested(ByVal sender As Object, ByVal e As RadComboBoxItemsRequestedEventArgs)
Dim sql As String = "SELECT [SupplierID], [CompanyName], [ContactName], [City] FROM [Suppliers] WHERE CompanyName LIKE @CompanyName + '%'"
Dim adapter As New SqlDataAdapter(sql, ConfigurationManager.ConnectionStrings("NorthwindConnectionString").ConnectionString)
adapter.SelectCommand.Parameters.AddWithValue("@CompanyName", e.Text)
Dim dt As New DataTable()
adapter.Fill(dt)
Dim comboBox As RadComboBox = DirectCast(sender, RadComboBox)
' Clear the default Item that has been re-created from ViewState at this point.
comboBox.Items.Clear()
For Each row As DataRow In dt.Rows
Dim item As New RadComboBoxItem()
item.Text = row("CompanyName").ToString()
item.Value = row("SupplierID").ToString()
item.Attributes.Add("ContactName", row("ContactName").ToString())
comboBox.Items.Add(item)
item.DataBind()
Next
End Sub
Protected Sub OnSelectedIndexChangedHandler(ByVal sender As Object, ByVal e As RadComboBoxSelectedIndexChangedEventArgs)
Session("SupplierID") = e.Value
End Sub
For additional information you can review this code library .