HandyOrg
Access Selected Items in CheckComboBox
I try to access to the Selected Items of the CheckComboBox. The goal is, to be able to selected Columns of a Table that you want to show. It seem like there is no way to do it in a MVVM achitecture.
The first way I was thinking is : <hc:CheckComboBox SelectedItems="{Binding MySelectedList}" /> but according to the issue #485 the SelectedItems is not a Property.
I found another way that not working but suppose to ^^. It is to create a class Item with 2 properties : Name and Selected and link them to the Property DisplayMemberPath and SelectedValuePath, see example below :
Model/Item.cs
public class Item{
public string Name { get; set; }
public bool Selected { get; set; }
}
ViewModel/MainWindowViewModel.cs
public class MainWindowViewModel{
public ObservableCollections<Item> MyItemList { get; set; } = new ObservableCollections<Item>() {
new Item() { Name = "column", Selected = true},
new Item() { Name = "column", Selected = true},
new Item() { Name = "column", Selected = false},
new Item() { Name = "column", Selected = false},
}
}
View/MainWindow.xaml
<hc:CheckComboBox Width="300" ItemsSource="{Binding MyItemList }" ShowClearButton="True"
ShowSelectAllButton="True" MaxHeight="30" DisplayMemberPath="Name" SelectedValuePath="Selected"/>
Is there a way to access to Selected Items without using the code behind (.xaml.cs) ? Is there an improvement to make in the CheckComboBox ?
Hi 🖐,
Here a little exemple how I make it work :
MainWindow.xaml.cs :
public partial class MainWindow : Window
{
public List<Item> Items { get; set; }
public MainWindow()
{
InitializeComponent();
DataContext = this;
Items = new List<Item>();
for (int i = 0; i < 15; i++)
Items.Add(new Item($"Item {i}", i));
// Here CheckComboBox refer to the hc:CheckComboBox x:Name="CheckComboBox"
CheckComboBox.ItemsSource = Items;
// Here, I select the first three items
for (int i = 0; i < 3; i++)
CheckComboBox.SelectedItems.Add(Items[i]);
}
private void CheckComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
foreach (Item item in e.AddedItems)
// For on each add Items
// do what you want
foreach (Item item in e.RemovedItems)
// For on each removed Items
// do what you want
}
}
and the xaml : MainWindow.xaml :
<Window x:Class="Wpf_Test.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:Wpf_Test"
xmlns:hc="https://handyorg.github.io/handycontrol"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800"
Background="Gray">
<StackPanel>
<hc:CheckComboBox x:Name="CheckComboBox"
SelectionChanged="CheckComboBox_SelectionChanged"
DisplayMemberPath="Name"
ShowClearButton="True"
ShowSelectAllButton="True"/>
</StackPanel>
</Window>
Hope it can help !
mvvm solutions:
here is : Attached Dependency Property
public class CheckComBoxHelper { static bool _isUpdating = false;
public static readonly DependencyProperty SelectedItemsProperty =
DependencyProperty.RegisterAttached("SelectedItems", typeof(List<string>), typeof(CheckComBoxHelper),
new FrameworkPropertyMetadata(null, new PropertyChangedCallback(OnPropertyChanged)));
public static List<string> GetSelectedItems(DependencyObject d)
{
return d.GetValue(SelectedItemsProperty) as List<string>;
}
public static void SetSelectedItems(DependencyObject d, List<string> value)
{
d.SetValue(SelectedItemsProperty, value);
}
private static void OnPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
CheckComboBox checkComboBox = d as CheckComboBox;
if (!_isUpdating)
{
var result = e.NewValue as List<string>;
checkComboBox.SelectedItems.Clear();
if (result != null)
{
foreach (var item in (List<string>)e.NewValue)
{
checkComboBox.SelectedItems.Add(item);
}
}
else
{
checkComboBox.SelectedItems.Add(e.NewValue);
}
}
}
public static readonly DependencyProperty AttachProperty =
DependencyProperty.RegisterAttached("Attach", typeof(bool), typeof(CheckComBoxHelper),
new FrameworkPropertyMetadata(default(bool), new PropertyChangedCallback(OnAttached)));
public static bool GetAttach(DependencyObject d)
{
return (bool)d.GetValue(AttachProperty);
}
public static void SetAttach(DependencyObject d, bool value)
{
d.SetValue(AttachProperty, value);
}
private static void OnAttached(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
CheckComboBox checkComboBox = d as CheckComboBox;
checkComboBox.SelectionChanged += CheckComboxSelectionChanged;
}
private static void CheckComboxSelectionChanged(object sender, RoutedEventArgs e)
{
CheckComboBox checkComboBox = sender as CheckComboBox;
_isUpdating = true;
List<string> temp = new List<string>();
foreach (var item in checkComboBox.SelectedItems)
{
temp.Add(item.ToString());
}
SetSelectedItems(checkComboBox, temp);
_isUpdating = false;
}
}
xaml:
<hc:CheckComboBox ItemsSource="{Binding CurrentUser.ModuleItems}"
ShowSelectAllButton="True"
common:CheckComBoxHelper.Attach="True"
common:CheckComBoxHelper.SelectedItems="{Binding CurrentUser.SelectItems,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Style="{StaticResource CheckComboBoxPlus}" hc:InfoElement.Necessary="True" />
