.NET MAUI ComboBox Selection
The .NET MAUI ComboBox enables the app users to quickly select item/items from the dropdown list. This topic will go through the provided by the ComboBox API related to item/items selection.
ComboBox control has a support for single and multiple selection. You can specify the required selection using the SelectionMode
property.
Main Properties
-
SelectionMode
(enumeration of typeTelerik.Maui.Controls.ComboBoxSelectionMode
)—Defines whether the selection is single or multiple. -
SelectedIndex
(int
)—Specifies the index of the first item in the current selection or -1 if the selection is empty. -
SelectedItem
(object
)—Defines the first item in the current selection, or null if the selection is empty. -
SelectedItems
(readonly ObservableCollection <object >
)—Gets the collection of currently Selected Items.
SelectedItems
collection can be changed only whenSelectionMode
isMultiple
. ForSingle
SelectionMode
useSelectedItem
.
Single Selection
The default SelectinMode
(enumeration of type Telerik.Maui.Controls.ComboBoxSelectionMode
) of the ComboBox control is Single
.
Example with Single Selection and SelectedIndex set
Here is the RadComboBox
definition in XAML:
<telerik:RadComboBox ItemsSource="{Binding Items}"
SelectionMode="Single"
DisplayMemberPath="Name"
SelectedIndex="{Binding SelectedIndex, Mode=TwoWay}"
SelectedItem="{Binding SelectedCity, Mode=TwoWay}"
AutomationId="comboBox"/>
you need to add the following namespace:
xmlns:telerik="http://schemas.telerik.com/2022/xaml/maui"
public class City
{
public string Name { get; set; }
public int Population { get; set; }
}
and the ViewModel used:
public class ViewModel: NotifyPropertyChangedBase
{
private int selectedIndex;
private City selectedCity;
public ViewModel()
{
this.Items = new ObservableCollection<City>
{
new City { Name = "Tokyo", Population = 13929286 },
new City { Name = "New York", Population = 8623000 },
new City { Name = "London", Population = 8908081 },
new City { Name = "Madrid", Population = 3223334 },
new City { Name = "Los Angeles", Population = 4000000},
new City { Name = "Paris", Population = 2141000 },
new City { Name = "Beijing", Population = 21540000 },
new City { Name = "Singapore", Population = 5612000 },
new City { Name = "New Delhi", Population = 18980000 },
new City { Name = "Bangkok", Population = 8305218 },
new City { Name = "Berlin", Population = 3748000 },
};
}
public ObservableCollection<City> Items { get; set; }
public int SelectedIndex
{
get => this.selectedIndex;
set => UpdateValue(ref this.selectedIndex, value);
}
public City SelectedCity
{
get => this.selectedCity;
set => UpdateValue(ref this.selectedCity, value);
}
}
This is how single selection looks:
Example with Multiple Selection and SelectedItems set
Here is the ComboBox definition in XAML:
<telerik:RadComboBox ItemsSource="{Binding Items}"
SelectionMode="Multiple"
DisplayMemberPath="Name"
Placeholder="Please select one or more cities"
SelectedItems="{Binding SelectedCities}"
SelectionChanged="RadComboBox_SelectionChanged"
AutomationId="selectedItemMultipleCombo" />
the sample business model
public class City
{
public string Name { get; set; }
public int Population { get; set; }
}
and the ViewModel used:
public class ViewModel : NotifyPropertyChangedBase
{
private ObservableCollection<object> selectedCities;
public ViewModel()
{
this.Items = new ObservableCollection<City>
{
new City { Name = "Tokyo", Population = 13929286 },
new City { Name = "New York", Population = 8623000 },
new City { Name = "London", Population = 8908081 },
new City { Name = "Madrid", Population = 3223334 },
new City { Name = "Los Angeles", Population = 4000000},
new City { Name = "Paris", Population = 2141000 },
new City { Name = "Beijing", Population = 21540000 },
new City { Name = "Singapore", Population = 5612000 },
new City { Name = "New Delhi", Population = 18980000 },
new City { Name = "Bangkok", Population = 8305218 },
new City { Name = "Berlin", Population = 3748000 },
};
}
public ObservableCollection<City> Items { get; set; }
public ObservableCollection<object> SelectedCities
{
get
{
return this.selectedCities;
}
set
{
if (this.selectedCities != value)
{
this.selectedCities = value;
this.selectedCities.Add(this.Items[0]);
this.selectedCities.Add(this.Items[1]);
this.OnPropertyChanged();
}
}
}
}
This is how multiple selection looks:
The Selection example can be found in our SDK Browser Application. You can find the applications in the Examples folder of your local Telerik UI for .NET MAUI installation or in the following GitHub repo.
Events
ComboBox exposes a SelectionChanged
event which is raised when item is selected.
The SelectionChanged
event handler receives two parameters:
- The
sender
which is the RadComboBox control. -
ComboBoxSelectionChangedEventArgs
provides the following properties:-
AddedItems
: the items added to the SelectedItemsCollection -
RemovedItems
: the items removed from the SelectedItemsCollection
-
Commands
ComboBox has two commands related to the Selection feature:
-
SelectAllCommand
(ICommand
)—Selects all items from the source. -
ClearSelectionCommand
(ICommand
)—Sets the selection to null. If Multiple SelectionMode is used, this command will clear all selected items.