c# - Filter items of a ListBox based on the text of a TextBox using only XAML in WPF

Question

I currently have a ListBox binded to a collection of items. As the collection is big we want to filter the items being shown based on the text entered on a TextBox.

What I'm asking is if this is possible to implement using only XAML, I don't want to modify the collection of items, I would like to modify the Visibility of each of the items based on the filter.

Hope its clear,

thanks!

Answer 1

Like CodeNaked and devdigital told you CollectionViewSource/CollectionView/ICollectionView are the keys to your goal

It's a MVVM patter but this is a View only related problem so I don't want this code at the ViewModel.

thats not the right way because the View only shows what she get′s but shouldn′t modifi so it should/must be your ViewModel who handel changes

so now some code snips:

    public class myVM
    {
        public CollectionViewSource CollViewSource { get; set; }
        public string SearchFilter
        {
            get;
            set
            {
              if(!string.IsNullOrEmpty(SearchFilter))
                 AddFilter();

                CollViewSource.View.Refresh(); // important to refresh your View
            }
        }
        public myVM(YourCollection)
        {
            CollViewSource = new CollectionViewSource();//onload of your VM class
            CollViewSource.Source = YourCollection;//after ini YourCollection
        }
    }

Xaml Snip:

    <StackPanel>
        <TextBox Height="23" HorizontalAlignment="Left"  Name="tB" VerticalAlignment="Top" 
                 Width="120" Text="{Binding SearchFilter,UpdateSourceTrigger=PropertyChanged}" />
        <DataGrid Name="testgrid" ItemsSource="{Binding CollViewSource.View}"/>
    </StackPanel>

Edit i forgot the Filter

private void AddFilter()
{
    CollViewSource.Filter -= new FilterEventHandler(Filter);
    CollViewSource.Filter += new FilterEventHandler(Filter);  

}

private void Filter(object sender, FilterEventArgs e)
{
    // see Notes on Filter Methods:
    var src = e.Item as YourCollectionItemTyp;
    if (src == null)
        e.Accepted = false;
    else if ( src.FirstName !=null && !src.FirstName.Contains(SearchFilter))// here is FirstName a Property in my YourCollectionItem
        e.Accepted = false;
}