Multicolumn Radcombox insert a blank item

[Calsh]

Hi

Using a Multicolumn Combobox with OpenAccess and trying to insert a blank item - as need to
 have the option of not selecting any item from the list - tried various solutions/posts with no success - code for combobox as below

 

<telerik:RadComboBox runat="server" ID="RadComboBox1" Height="190px" Width="100%"

    MarkFirstMatch="true" DataSourceID="OpenAccessLinqDataSource1" EnableLoadOnDemand="true"

    HighlightTemplatedItems="true" DataValueField="PartID" DataTextField="PartNumber"

    AppendDataBoundItems="True" SelectedValue='<%# Bind("PartID") %>' ItemsPerRequest="10"

    EnableVirtualScrolling="True" Filter="Contains" OnSelectedIndexChanged="RadComboBox1_SelectedIndexChanged"

    AutoPostBack="True">

    <HeaderTemplate>

        <ul>

            <li class="col1">Part Number</li>

            <li class="col2">Part Description</li>

        </ul>

    </HeaderTemplate>

    <ItemTemplate>

        <ul>

            <li class="col1">

                <%# DataBinder.Eval(Container.DataItem, "PartNumber")%>

            </li>

            <li class="col2">

                <%# DataBinder.Eval(Container.DataItem, "PartDescription")%></li>

        </ul>

    </ItemTemplate>

</telerik:RadComboBox>

Tried online demo http://www.telerik.com/help/aspnet-ajax/combobox-insert-default-item-when-databinding.html 

 Thanks

 

[Shinu]

Hi Calsh,

Please have a look into the complete code to insert a blank Item in RadMultiColumComboBox.

ASPX:

<telerik:RadComboBox runat="server" ID="RadComboBox1" Height="190px" Width="420px"
    AppendDataBoundItems="true" AutoPostBack="true" NoWrap="true">
    <HeaderTemplate>
        <ul>
            <li class="col1">City Name</li>
            <li class="col2">Country Name</li>
        </ul>
    </HeaderTemplate>
    <ItemTemplate>
        <ul>
            <li class="col1">
                <%# Container.DataItem != null ? DataBinder.Eval(Container.DataItem, "Cityname") : DataBinder.Eval(Container, "Text")%>
            </li>
            <li class="col2">
                <%# Container.DataItem != null ? DataBinder.Eval(Container.DataItem, "Cityname") : DataBinder.Eval(Container, "Text")%>
            </li>
        </ul>
    </ItemTemplate>
    <Items>
        <telerik:RadComboBoxItem Text="" />
    </Items>
</telerik:RadComboBox>

C#:

protected void Page_Load(object sender, EventArgs e)
{
    RadComboBox1.DataBind();
    String connstring = WebConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
    SqlConnection conn = new SqlConnection(connstring);
    SqlDataAdapter adapter = new SqlDataAdapter();
    adapter.SelectCommand = new SqlCommand("SELECT [Cityname], [Countryname] FROM [City]", conn);
    DataTable data = new DataTable();
    conn.Open();
    try
    {
        adapter.Fill(data);
    }
    finally
    {
        conn.Close();
    }
    RadComboBox1.DataSource = data;
    RadComboBox1.DataTextField = "Cityname";
    RadComboBox1.DataValueField = "Countryname";
    RadComboBox1.DataBind();
}

Hope this will helps you.
Thanks,
Shinu.

[Calsh]

I'm using VB - changed as below - which puts a blank item in the combobox - but get error '   is not a valid value for Int32'  when 'update' record - the field being updated is int32 and allows nulls and acts as a lookup to another table

(Using OpenAccess with simple binding and edit form template to allow editing of record)

<li class="col1">

    <%# If(Container.DataItem IsNot Nothing, DataBinder.Eval(Container.DataItem, "PartNumber"), DataBinder.Eval(Container, "Text"))%>

</li>

Thanks

[Shinu]

Hi Calsh,

I guess your RadComboBox is inside another control.(Here for example inside RadGrid). I have tried a sample scenario and was able to update the data. Please have a look into the following code.
ASPX:

<telerik:RadGrid ID="RadGrid1" runat="server" DataSourceID="SqlDataSource1" AllowAutomaticUpdates="true">
    <MasterTableView DataSourceID="SqlDataSource1" AutoGenerateColumns="False" DataKeyNames="EmployeeID">
        <Columns>
            <telerik:GridEditCommandColumn>
            </telerik:GridEditCommandColumn>
            <telerik:GridBoundColumn DataField="EmployeeID" DataType="System.Int32" FilterControlAltText="Filter OrderID column"
                HeaderText="EmployeeID" SortExpression="EmployeeID" UniqueName="EmployeeID">
            </telerik:GridBoundColumn>
            <telerik:GridBoundColumn DataField="ReportsTo" FilterControlAltText="Filter CustomerID column"
                HeaderText="ReportsTo" SortExpression="ReportsTo" UniqueName="ReportsTo">
            </telerik:GridBoundColumn>
        </Columns>
        <EditFormSettings EditFormType="Template">
            <FormTemplate>
                <telerik:RadComboBox runat="server" ID="RadComboBox1" Height="190px" Width="420px"
                    AppendDataBoundItems="true" AutoPostBack="true" NoWrap="true" DataSourceID="SqlDataSource1"
                    DataTextField="EmployeeID" DataValueField="EmployeeID">
                    <HeaderTemplate>
                        <ul>
                            <li class="col1">EmployeeID</li>
                            <li class="col2">ReportsTo</li>
                        </ul>
                    </HeaderTemplate>
                    <ItemTemplate>
                        <ul>
                            <li class="col1">
                                <%# Container.DataItem != null ? DataBinder.Eval(Container.DataItem, "EmployeeID") : DataBinder.Eval(Container, "Text")%>
                            </li>
                            <li class="col2">
                                <%# Container.DataItem != null ? DataBinder.Eval(Container.DataItem, "ReportsTo") : DataBinder.Eval(Container, "Text")%>
                            </li>
                        </ul>
                    </ItemTemplate>
                    <Items>
                        <telerik:RadComboBoxItem Text="" />
                    </Items>
                </telerik:RadComboBox>
                <asp:Button ID="btnUpdate" Text="Update" runat="server" CommandName="Update"></asp:Button>
            </FormTemplate>
        </EditFormSettings>
    </MasterTableView>
</telerik:RadGrid>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
    SelectCommand="SELECT top 5 [EmployeeID], [LastName],[ReportsTo] FROM [EmployeeDetails]"
    UpdateCommand="UPDATE [EmployeeDetails] SET [ReportsTo] = @ReportsTo WHERE [EmployeeID] = @EmployeeID">
    <UpdateParameters>
        <asp:Parameter Name="ReportsTo" Type="Int32"></asp:Parameter>
        <asp:Parameter Name="EmployeeID" Type="Int32"></asp:Parameter>
    </UpdateParameters>
</asp:SqlDataSource>

Please make sure that your updating column allows null value to add into database table. For more help, please provide your complete code.

Thanks,
Shinu.
 

[Calsh]

Tried as you suggested - but still no luck - the database field that is being updated allows nulls

I'm using a GridDropDownColumn that is bound to a different data source than the RadGrid - got a solution by adding a blank item in the RadGrid_ItemDataBound Event as code below (removed other columns etc. to make it easier to read) - used this code to add a blank item to other dropdown lists (copied it but can't remember where found it) - the only disadvantage to this method is that the blank item appears at the bottom of the list - but otherwise works OK

<telerik:RadGrid runat="server" DataSourceID="OpenAccessLinqDataSourceItems"
    AllowAutomaticDeletes="True" AllowAutomaticInserts="True"
    AllowAutomaticUpdates="True" ID="RadGridItems" AutoGenerateColumns="False">

    <MasterTableView DataKeyNames="ItemID" DataSourceID="OpenAccessLinqDataSourceItems" EditMode="PopUp">
        <Columns>
            <telerik:GridDropDownColumn FilterControlAltText="Filter Part column" UniqueName="PartID"
                DataSourceID="OpenAccessLinqDataSourceParts" DataField="PartID" HeaderText="Part Number"
                SortExpression="PartID" ListValueField="PartID" AllowSorting="true" ListTextField="PartNumber"
                DropDownControlType="DropDownList">
            </telerik:GridDropDownColumn>
        </Columns>

        <EditFormSettings EditFormType="Template">
            <FormTemplate>
                <telerik:RadComboBox runat="server" ID="RadComboBox1"
            DataSourceID="OpenAccessLinqDataSourceParts" EnableLoadOnDemand="true"
                            DataValueField="PartID" DataTextField="PartNumber"
                            AppendDataBoundItems="True" SelectedValue='<%# Bind("PartID") %>'
                            AutoPostBack="True" >
                        <HeaderTemplate>
                            <ul>
                                    <li class="col1">Part Number</li>
                                        <li class="col2">Part Description</li>
                                </ul>
                        </HeaderTemplate>
                            <ItemTemplate>
                                <ul>
                                            <li class="col1">
                                                <%# DataBinder.Eval(Container.DataItem, "PartNumber")%>
                                            </li>
                                            <li class="col2">
                                                    <%# DataBinder.Eval(Container.DataItem, "PartDescription")%>
                                            </li>
                                    </ul>
                            </ItemTemplate>
                    </telerik:RadComboBox>
    </FormTemplate>
        </EditFormSettings>

    </MasterTableView>
</telerik:RadGrid>



Private Sub RadGridItems_ItemDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridItemEventArgs) Handles RadGridItems.ItemDataBound


    If (TypeOf e.Item Is GridEditableItem AndAlso e.Item.IsInEditMode) Then
        Dim editItem As GridEditFormItem = DirectCast(e.Item, GridEditFormItem)

        comboBoxPartID = (TryCast(editItem.FindControl("RadComboBox1"), RadComboBox))
        selectedPartIDValue = comboBoxPartID.SelectedValue
        With comboBoxPartID
            .Items.Add(New RadComboBoxItem("", "0"))

            If selectedPartIDValue = " " Then
                .SelectedValue = CStr(0)
            Else
                .SelectedValue = selectedPartIDValue
            End If
        End With

    End If

End Sub