Combo box cell displays an editable drop-down list within a cell. Users can expand the drop-down list by clicking the drop-down button, by pressing the F4, or Alt + Down arrow.

You can configure a combo box cell using the methods and properties of the ComboBoxCellType class in the GrapeCity.Wpf.SpreadSheet.CellType namespace. There are two primary methods of configuring items in a combo box cell:

• Binding the combo box cell to a data source
  • Set the data source in the ItemsSource property.
  • Specify the field name to display the items in the ContentPath property.
  • Define the field name to be used as the cell value when an item is selected in the SelectedValuePath property.

  The following sample code binds a combo box cell to a ProductCollection().

  • C#
  • VB

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  private void Window_Loaded(object sender, RoutedEventArgs e) { // Set items with data binding. GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType comboBound = new GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType { ItemsSource = new ProductCollection(), ContentPath = "Name", SelectedValuePath = "ID" }; spreadSheet1.Workbook.ActiveSheet.Columns[0].CellType = comboBound; } public class Product : System.ComponentModel.INotifyPropertyChanged { string id; string name; public string ID { set { id = value; NotifyPropertyChanged("ID"); } get { return id; } } public string Name { set { name = value; NotifyPropertyChanged("Name"); } get { return name; } } public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged; protected void NotifyPropertyChanged(string propertyName) { if (PropertyChanged != null) PropertyChanged(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName)); } } internal class ProductCollection : System.Collections.ObjectModel.ObservableCollection<Product> { public ProductCollection() { Add(new Product() { ID = "CUPTNS0001", Name = "John Miller" }); Add(new Product() { ID = "CUPTND0002", Name = "Tom Martin" }); Add(new Product() { ID = "CUPTNF0003", Name = "Paul Walker" }); Add(new Product() { ID = "CUPSCO0004", Name = "Harry Shang" }); Add(new Product() { ID = "CUPSCA0005", Name = "Joe Jonas" }); } }

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  Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs) ' Set items with data binding. Dim comboBound As GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType = New GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType With { .ItemsSource = New ProductCollection(), .ContentPath = "Name", .SelectedValuePath = "ID" } spreadSheet1.Workbook.ActiveSheet.Columns(0).CellType = comboBound End Sub Public Class Product Implements ComponentModel.INotifyPropertyChanged Private idField As String Private nameField As String Public Property ID As String Set(value As String) idField = value NotifyPropertyChanged("ID") End Set Get Return idField End Get End Property Public Property Name As String Set(value As String) nameField = value NotifyPropertyChanged("Name") End Set Get Return nameField End Get End Property Public Event PropertyChanged As ComponentModel.PropertyChangedEventHandler Implements ComponentModel.INotifyPropertyChanged.PropertyChanged Protected Sub NotifyPropertyChanged(propertyName As String) RaiseEvent PropertyChanged(Me, New ComponentModel.PropertyChangedEventArgs(propertyName)) End Sub End Class Friend Class ProductCollection Inherits ObjectModel.ObservableCollection(Of Product) Public Sub New() Add(New Product() With { .ID = "CUPTNS0001", .Name = "John Miller" }) Add(New Product() With { .ID = "CUPTND0002", .Name = "Tom Martin" }) Add(New Product() With { .ID = "CUPTNF0003", .Name = "Paul Walker" }) Add(New Product() With { .ID = "CUPSCO0004", .Name = "Harry Shang" }) Add(New Product() With { .ID = "CUPSCA0005", .Name = "Joe Jonas" }) End Sub End Class

• Setting unbound data in the data source
  • Use the Items property to reference the collection of items and the Add method to add item data. 
  • If the combo box cell is not bound to a data source, the string displayed in the item will represent the cell's value.
    This behavior can be adjusted using the ValueType property.

  The following example code sets items in a combo box cell that are not bound to a data source.

  • C#
  • VB

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  // Set unbound items. GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType comboUnbound = new GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType(); comboUnbound.Items.Add("Japanese"); comboUnbound.Items.Add("Korean"); comboUnbound.Items.Add("Chinese"); comboUnbound.Items.Add("German"); comboUnbound.Items.Add("French"); spreadSheet1.Workbook.ActiveSheet.Columns[2].CellType = comboUnbound;

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  ' Set unbound items. Dim comboUnbound As GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType = New GrapeCity.Wpf.SpreadSheet.CellType.ComboBoxCellType() comboUnbound.Items.Add("Japanese") comboUnbound.Items.Add("Korean") comboUnbound.Items.Add("Chinese") comboUnbound.Items.Add("German") comboUnbound.Items.Add("French") spreadSheet1.Workbook.ActiveSheet.Columns(2).CellType = comboUnbound

Additionally, the drop-down list of a combo box cell can also display items in multiple columns. To enable the multi-column feature of a combo box cell and display items in multiple columns within the drop-down list, set the UseMultipleColumn property to true.

The following example code binds a combo box cell to a CellTypeCollection and enables the multi-column feature.

private void Window_Loaded(object sender, RoutedEventArgs e)
{
     // Multi - column combo box.
     ComboBoxCellType c = new ComboBoxCellType();
     c.ItemsSource = new CellTypeCollection();
     c.ContentPath = "Name";
     c.UseMultipleColumn = true;
     c.DropDownWidth = 400;
     spreadSheet1.Workbook.ActiveSheet.Columns[0].CellType = c;
     spreadSheet1.Workbook.ActiveSheet.Columns[0].ColumnWidth = 400;
}

public class CellTypeCollection : List<SpreadCellType>
{
     public CellTypeCollection()
     {
            Add(new SpreadCellType()
            {
                Display = new BitmapImage(new Uri(@"Images\TextCellType.png", UriKind.Relative)),
                Name = "Text",
                Description = "Only permitted character types can be entered."
            });
            Add(new SpreadCellType()
            {
                Display = new BitmapImage(new Uri(@"Images\DateCellType.png", UriKind.Relative)),
                Name = "DateTime",
                Description = "You can enter a date and time."
            });
            Add(new SpreadCellType()
            {
                Display = new BitmapImage(new Uri(@"Images\NumberCellType.png", UriKind.Relative)),
                Name = "Number",
                Description = "You can enter a number."
            });
            Add(new SpreadCellType()
            {
                Display = new BitmapImage(new Uri(@"Images\ComboCellType.png", UriKind.Relative)),
                Name = "ComboBox",
                Description = "Select data from the combo box."
            });
            Add(new SpreadCellType()
            {
                Display = new BitmapImage(new Uri(@"Images\ButtonCellType.png", UriKind.Relative)),
                Name = "Button",
                Description = "Show the button."
            });
     }
}

Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    ' Multi - column combo box.
    Dim c As ComboBoxCellType = New ComboBoxCellType()
    c.ItemsSource = New CellTypeCollection()
    c.ContentPath = "Name"
    c.UseMultipleColumn = True
    c.DropDownWidth = 400
    spreadSheet1.Workbook.ActiveSheet.Columns(0).CellType = c
    spreadSheet1.Workbook.ActiveSheet.Columns(0).ColumnWidth = 400
End Sub

Public Class CellTypeCollection
    Inherits List(Of SpreadCellType)
    Public Sub New()
        Add(New SpreadCellType() With {
        .Display = New BitmapImage(New Uri("Images\TextCellType.png", UriKind.Relative)),
        .Name = "Text",
        .Description = "Only permitted character types can be entered."
        })
        Add(New SpreadCellType() With {
        .Display = New BitmapImage(New Uri("Images\DateCellType.png", UriKind.Relative)),
        .Name = "DateTime",
        .Description = "You can enter a date and time."
        })
        Add(New SpreadCellType() With {
        .Display = New BitmapImage(New Uri("Images\NumberCellType.png", UriKind.Relative)),
        .Name = "Number",
        .Description = "You can enter a number."
        })
        Add(New SpreadCellType() With {
        .Display = New BitmapImage(New Uri("Images\ComboCellType.png", UriKind.Relative)),
        .Name = "ComboBox",
        .Description = "Select data from the combo box."
        })
        Add(New SpreadCellType() With {
        .Display = New BitmapImage(New Uri("Images\ButtonCellType.png", UriKind.Relative)),
        .Name = "Button",
        .Description = "Show the button."
        })
    End Sub
End Class