Filter a DataGrid in WPF

This is a simple implementation of using the Filter property of ICollectionView. Suppose your XAML contains this:

<TextBox x:Name="SearchTextBox" />
<Button x:Name="SearchButton"
        Content="Search"
        Click="SearchButton_OnClick"
        Grid.Row="1" />
<DataGrid x:Name="MyDataGrid"
          Grid.Row="2">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Lorem ipsum column"
                            Binding="{Binding}" />
    </DataGrid.Columns>
</DataGrid>

Then in the constructor you can get the default view for your data where you can set the filter predicate which will be executed for every item of your collection. The CollectionView won't know when it should update the collection, so you have to call Refresh when the user clicks the search button.

private ICollectionView defaultView;

public MainWindow()
{
    InitializeComponent();

    string[] items = new string[]
    {
        "Asdf",
        "qwer",
        "sdfg",
        "wert",
    };

    this.defaultView = CollectionViewSource.GetDefaultView(items);
    this.defaultView.Filter =
        w => ((string)w).Contains(SearchTextBox.Text);

    MyDataGrid.ItemsSource = this.defaultView;
}

private void SearchButton_OnClick(object sender, RoutedEventArgs e)
{
    this.defaultView.Refresh();
}

At this url you can find a more detailed description of CollectionViews: http://wpftutorial.net/DataViews.html

@WiiMaxx, can't comment as not enough rep. I would be a bit more careful about the direct casts there. They can be slow for one thing and for another, if the same filter was applied to a grid holding different complex type data you would have an InvalidCastException.

// your Filter
    var yourCostumFilter= new Predicate<object>(item =>
    {
        item = item as Model;
        return item == null || item.Name.Contains("Max");
    });

This will not break you datagrid and will not filter the results if the cast fails. Less impact to your users if you get the code wrong. On top of that the filter will be faster due to the "as" operator not doing any explicit type coercion as the direct cast operation will.

there are multiple way's to filter Collection

let's suggesting this is your Item Class

public class Model
{
    public string Name
    {
        get;
        set;
    }
}

and your collection looks like

       var ObColl = new ObservableCollection<Model>();

        ObColl.Add(new Model() { Name = "John" });
        ObColl.Add(new Model() { Name = "Karl" });
        ObColl.Add(new Model() { Name = "Max" });
        ObColl.Add(new Model() { Name = "Mary" });

Way 1 (Predicate):

    public MainWindow()
    {
        InitializeComponent();

        // Collection which will take your ObservableCollection
        var _itemSourceList = new CollectionViewSource() { Source = ObColl };

        // ICollectionView the View/UI part 
        ICollectionView Itemlist = _itemSourceList.View;

        // your Filter
        var yourCostumFilter= new Predicate<object>(item => ((Model)item).Name.Contains("Max"));

        //now we add our Filter
        Itemlist.Filter = yourCostumFilter;

        dataGrid1.ItemsSource = Itemlist;
    }

Way 2 (FilterEventHandler):

    public MainWindow()
    {
        InitializeComponent();

        // Collection which will take your Filter
        var _itemSourceList = new CollectionViewSource() { Source = ObColl };

       //now we add our Filter
       _itemSourceList.Filter += new FilterEventHandler(yourFilter);

        // ICollectionView the View/UI part 
        ICollectionView Itemlist = _itemSourceList.View;

        dataGrid1.ItemsSource = Itemlist;
    }

    private void yourFilter(object sender, FilterEventArgs e)
    {
        var obj = e.Item as Model;
        if (obj != null)
        {
            if (obj.Name.Contains("Max"))
                e.Accepted = true;
            else
                e.Accepted = false;
        }
    }

extended Information to Way 1

if need multiple conditions or some complex Filter you can add a method to your Predicat

    // your Filter
    var yourComplexFilter= new Predicate<object>(ComplexFilter);

    private bool ComplexFilter(object obj)
    {
        //your logic
    }