We're currently using a radmulticolumncombobox populated through a dataset, and need the capability of selecting a blank row. Within our database the field it refers to is non-null, and the client has to be able to select nothing for a value.
I've tried using lstParentGroup.EditorControl.Rows.AddNew(), but this adds the row to the very bottom of the collection. We definitely want the blank row at the top of the list. Also, when this row is added, the control seems to get confused when using lstParentGroup.SelectedValue functionality. What happens is the blank row at the bottom is selected instead of what should be selected.
Anything I've missed in the designer, or possible solutions to this problem?
Thank you very much for your time!
Ryan
7 Answers, 1 is accepted
Thank you for writing.
You can add dummy row in your DataSource and pin the related GridViewRowInfo instance to the top in order to achieve your scenario. Here is a sample application with DataTable binding and the event handler implementation:
using System;using System.Data;using Telerik.WinControls.UI;namespace Lab.Combo{ public partial class MultiComboEmptyRow : MainForm { private RadMultiColumnComboBox comboBox = new RadMultiColumnComboBox(); private DataRow emptyRow; public event EventHandler NoneSelected; public MultiComboEmptyRow() { InitializeComponent(); comboBox.Parent = this; comboBox.SelectedIndexChanged += comboBox_SelectedIndexChanged; } void comboBox_SelectedIndexChanged(object sender, EventArgs e) { GridViewRowInfo current = this.comboBox.EditorControl.CurrentRow; if (current != null) { DataRow row = (current.DataBoundItem as DataRowView).Row; if (row == emptyRow && this.NoneSelected != null) { this.NoneSelected(this, new EventArgs()); } } } protected override void OnLoad(EventArgs e) { base.OnLoad(e); DataTable table1 = new DataTable(); table1.Columns.Add("ID"); table1.Columns.Add("Name"); this.emptyRow = table1.Rows.Add(null, null); table1.Rows.Add(1, "Ivan Petrov"); table1.Rows.Add(2, "Stefan Muler"); table1.Rows.Add(3, "Alexandro Ricco"); this.comboBox.DataSource = table1; comboBox.DisplayMember = "Name"; SetTopEmptyRow(); } private void SetTopEmptyRow() { foreach (GridViewRowInfo row in this.comboBox.EditorControl.Rows) { if ((row.DataBoundItem as DataRowView).Row == this.emptyRow) { row.PinPosition = PinnedRowPosition.Top; break; } } } }}I hope this helps.
Regards,
Julian Benkov
the Telerik team
Rank 1
Thanks for your reply so far.
The main problem is that my combobox is already databound through a table adapter. I can create the new row and pin it to the top, but when it comes time to fill the table adapter again, Object Reference exceptions are raised because of the blank row. I can remove the row before filling then add it again, but this leads to a unique problem where two blank rows exist.
Thanks for your help
In this situation, you should remove the row from the PinPosition:
this.gridView.Rows[0].PinPosition = PinnedRowPosition.None;After that remove the row from the DataSource object and fill the DataSouce. Then you can add the empty row again and pin to top position.
I hope this helps.
Kind regards,
Julian Benkov
the Telerik team
Rank 1
Dim emptyRow As Telerik.WinControls.UI.GridViewRowInfo If emptyRow IsNot Nothing Then emptyRow.PinPosition = PinnedRowPosition.None End If Dim rows As New List(Of GridViewRowInfo)(Me.lstParentGroup.EditorControl.Rows) If rows.Any Then For Each row As Telerik.WinControls.UI.GridViewDataRowInfo In rows row.Delete() Next End If GroupByJobTableAdapter.FillByJobID(DataMain.GroupByJob, lstJob.SelectedValue) emptyRow = lstParentGroup.EditorControl.Rows.AddNew() emptyRow.PinPosition = PinnedRowPosition.Top emptyRow.Cells("GroupNo").Value = "None"Thank you very much for you help!
Cheers,
Ryan
I am glad to hear that you have solved your issue.
Feel free to ask if you have any additional questions.
Julian Benkov
the Telerik team
Rank 1
Hi!
I'm having the same issue. When i load data from Query into MultiColumnCB, and update the data by selecting from it. When i have last value left in MultiColumnCB, no index is changed. If there is another solution for it then i would appreciate. If not, then i will add an empty row for this to change the index and make the rest code work.
My code is:
Private Sub FwdDocQuery_SelectedIndexChanged(sender As Object, e As EventArgs) Handles FwdDocQuery.SelectedIndexChanged
StatusIDRadTextBox1.Text = "2"
If Not String.IsNullOrWhiteSpace(FwdDocQuery.Text) Then
Dim index As Integer = ApplicationsBindingSource.Find("ID", FwdDocQuery.Text)
If index > -1 Then
ApplicationsBindingSource.Position = index
End If
End If
If DocTypeIDRadTextBox1.Text = "1" Then
DocTypeTBFWD.Text = "Transcript"
ElseIf DocTypeIDRadTextBox1.Text = "2" Then
DocTypeTBFWD.Text = "Degree"
ElseIf DocTypeIDRadTextBox1.Text = "3" Then
DocTypeTBFWD.Text = "NOC"
End If
End Sub
If you need to delete the value in RadMultiColumnComboBox, simply press the Delete key while the editable part is focused. Thus, when you navigate the next control on the form, no value will be selected in RadMultiColumnComboBox.
Indeed, adding an empty row to the DataTable that is used for DataSource in RadMultiColumnComboBox is an appropriate solution to offer the user an option for selecting in the drop down. Thus, when you select the empty record, there is a dedicated value for it with an empty DisplayMember.
I hope this information helps.
Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik