wpf combobox event for 'item not found' - wpf

Question

can i know if text is not Compatible with no iten in list
<ComboBox IsEditable="True" ItemSource="..."/>
there is an event or property to determine if no item found by TextSearch

Answer 1

You could check the SelectedItem property on the ComboBox and if this is null while it is changing, it means that there is no match in the list. Here you have a small demo how it could work.
XAML part:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<ComboBox ItemsSource="{Binding ItemsSource, UpdateSourceTrigger=PropertyChanged}"
IsEditable="True"
Text="{Binding TypedText, UpdateSourceTrigger=PropertyChanged}"
Height="36"
VerticalAlignment="Top"/>
</Grid>
XAML.cs:
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
DataContext = new MainWindowVM();
}
}
and here the ViewModel:
public class MainWindowVM : INotifyPropertyChanged
{
private ObservableCollection<string> _itemsSource;
public ObservableCollection<string> ItemsSource
{
get { return _itemsSource; }
set
{
_itemsSource = value;
OnPropertyChanged("ItemsSource");
}
}
private string _typedText;
public string TypedText
{
get { return _typedText; }
set
{
_typedText = value;
OnPropertyChanged("TypedText");
//check if the typed text is contained in the items source list
var searchedItem = ItemsSource.FirstOrDefault(item => item.Contains(_typedText));
if (searchedItem == null)
{
//the item was not found. Do something
}
else
{
//do something else
}
}
}
public MainWindowVM()
{
if (ItemsSource == null)
{
ItemsSource = new ObservableCollection<string>();
}
for (int i = 0; i < 25; i++)
{
ItemsSource.Add("text" + i);
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
protected bool SetField<T>(ref T field, T value, string propertyName)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
}
I hope it helps.