How to: Filter a LookUp(ComboBox) Column Based on Another Column Value

Assume that a grid column's in-place editor provides a drop-down list of specific values, and the values must be filtered according to other row values. For instance, a grid contains two columns: the first column is used to edit a Country field, while the second column should provide a list of cities for the selected country. To display the appropriate values only, the second column's values should be filtered based on the first column's value.

Use a LookUpEdit or ComboBoxEdit in-place editor for a column whose drop-down values need to be filtered. When using a LookUpEdit editor, you can assign a list of items to be displayed in the drop-down directly to the editor's DataSource property. A ComboBoxEdit control doesn't provide this property. The drop-down list should be populated manually by adding items to the editor's Items collection.

To filter the column's drop-down values, handle the ColumnView.ShownEditor event. In this event, the active editor's drop-down list must be filtered as required. See the following code for an example.

To get the full source code of the example, refer to the following Knowledge Base article:

How to filter a second LookUp column based on a first LookUp column's value

C#: using DevExpress.XtraEditors; using DevExpress.XtraGrid.Views.Grid;   private DataView clone = null;   private void gridView1_ShownEditor(object sender, System.EventArgs e) {     GridView view = sender as GridView;     if (view.FocusedColumn.FieldName == "CityCode" && view.ActiveEditor is LookUpEdit) {         Text = view.ActiveEditor.Parent.Name;         DevExpress.XtraEditors.LookUpEdit edit;         edit = (LookUpEdit)view.ActiveEditor;           DataTable table = edit.Properties.LookUpData.DataSource as DataTable;         clone = new DataView(table);         DataRow row = view.GetDataRow(view.FocusedRowHandle);         clone.RowFilter = "[CountryCode] = " + row["CountryCode"].ToString();         edit.Properties.LookUpData.DataSource = clone;     } }   private void gridView1_HiddenEditor(object sender, System.EventArgs e) {     if (clone != null) {         clone.Dispose();         clone = null;     } }

VB: Imports DevExpress.XtraEditors Imports DevExpress.XtraGrid.Views.Grid   Private clone As DataView   Private Sub GridView1_ShownEditor(ByVal sender As Object, _   ByVal e As System.EventArgs) Handles GridView1.ShownEditor     Dim view As GridView = CType(sender, GridView)     If view.FocusedColumn.FieldName = "CityCode" AndAlso _       TypeOf view.ActiveEditor Is LookUpEdit Then         Dim edit As LookUpEdit         Dim table As DataTable         Dim row As DataRow           edit = CType(view.ActiveEditor, .LookUpEdit)           table = CType(edit.Properties.DataSource, DataTable)         clone = New DataView(table)         row = view.GetDataRow(view.FocusedRowHandle)         clone.RowFilter = "[CountryCode] = " + row("CountryCode").ToString()         edit.Properties.DataSource = clone     End If End Sub   Private Sub GridView1_HiddenEditor(ByVal sender As Object, _   ByVal e As System.EventArgs) Handles GridView1.HiddenEditor     If Not clone Is Nothing Then         clone.Dispose()         clone = Nothing     End If End Sub