Create simple datatrigger for datagrid programmatically with C#-CodePudding

I'm trying to do a simple example of a datatrigger programmatically in C# and don't get how it works. The datatrigger in XAML would work but I need it in C#. The rows in the datagrid should change their color if the number is 10.

My MainWindow.xaml.cs:

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        List<User> users = new List<User>();
        users.Add( new User() { Id = 1, Name = "John Doe", Number = 1 } );
        users.Add( new User() { Id = 2, Name = "Jane Doe", Number = 10 } );
        users.Add( new User() { Id = 3, Name = "Sammy Doe", Number = 10 } );
        users.Add( new User() { Id = 4, Name = "Anne Blanc", Number = 7 } );

        dgUsers.ItemsSource = users;
    }
}

public class User //: INotifyPropertyChanged
{
    public int Id
    {
        get; set;
    }

    public string Name
    {
        get; set;
    }

    // must be implemented as dependency property?
    //private int _number;
    public int Number
    {
        get; set;
        //get
        //{
        //    return _number;
        //}
        //set
        //{
        //    _number = value;
        //    OnPropertyChanged( "Number" );
        //}
    }

    //public event PropertyChangedEventHandler? PropertyChanged;

    //public void OnPropertyChanged( string propName )
    //{
    //    PropertyChangedEventHandler handler = PropertyChanged;
    //    if ( handler != null )
    //        handler( this, new PropertyChangedEventArgs( propName ) );
    //}
}

And this simple datatrigger in MainWindow.xaml works:

<Window x:Class="WpfGrid1.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:WpfGrid1"
        mc:Ignorable="d"
        Title="DataGridColumnsSample" Height="500" Width="500">
    <Grid Grid.Column="0" Margin="10">
        <DataGrid Name="dgUsers" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTextColumn Header="Name" Binding="{Binding Name}" Width="100" />
                <DataGridTextColumn Header="Number" Binding="{Binding Number}" />
            </DataGrid.Columns>

            <DataGrid.RowStyle>
                <Style TargetType="DataGridRow">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding Number}" Value="10">
                            <Setter Property="Foreground" Value="Red" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </DataGrid.RowStyle>
        </DataGrid>
    </Grid>
</Window>

Do I need to implement the interface INotifyPropertyChanged even if it works without it in XAML? I tried to implement it (see class User above). But I don't understand how to set the binding if I create the trigger programmatically in the C# code and not in the XAML file. My attempts (before or after the line dgUsers.ItemsSource = users;) were:

//this.DataContext = dgUsers.ItemsSource;

Binding bindingObjectNumber = new Binding();
//bindingObjectNumber.Mode = BindingMode.OneWay; // update target if source changes
bindingObjectNumber.Mode = BindingMode.TwoWay;
//bindingObjectNumber.Source = dgUsers;
//bindingObjectNumber.Source = dgUsers.ItemsSource;
bindingObjectNumber.Source = users;
bindingObjectNumber.Path = new PropertyPath( "Number" );
//bindingObjectNumber.RelativeSource = RelativeSource.Self;

DataTrigger dataTrigger = new DataTrigger();
dataTrigger.Binding = bindingObjectNumber;
dataTrigger.Value = "10";
dataTrigger.Setters.Add( new Setter( DataGrid.ForegroundProperty, Brushes.Red ) );

Style style = new Style();
style.Triggers.Add( dataTrigger );
this.Resources.Add( typeof( DataGrid ), style );

These links didn't help me as an absolute beginner in WPF.

Any help or explanation would be appreciated. Thank you very much.

CodePudding user response：

dgUsers.RowStyle = new Style
{
    TargetType = typeof(DataGridRow),
    Triggers = 
    {
        new DataTrigger
        {
            Binding = new Binding("Number"),
            Value = 10,
            Setters = 
            {
                new Setter( DataGrid.ForegroundProperty, Brushes.Red )
            }
        }
    }
};