Question

Ok, here is my situation:
I have a DataGridView containing Messages, to which the following style is applied.

<Style x:Key="ChangeSetRowStyle" TargetType="{x:Type DataGridRow}">
    <Setter Property="FontWeight" Value="Normal" />
    <Style.Triggers>
        <DataTrigger Binding="{Binding IsRead}" Value="False">
            <Setter Property="FontWeight" Value="Bold" />
        </DataTrigger>
        <DataTrigger Binding="{Binding IsRead}" Value="True">
            <Setter Property="FontWeight" Value="Normal" />
        </DataTrigger>
    </Style.Triggers>
</Style>

My intention is to make unread messages bold, while read messages stay with normal font weight. Even though the style is applied correctly when the collection is loaded, nothing changes when an item’s IsRead property is changed. It seems like the style just does’t update.

Can someone please shed some light on this? Thanks!

Answer 1

Your Message class needs to inherit from INotifyPropertyChanged and the IsRead property needs to raise the PropertyChanged event when modified. Here’s an example:

public class Message: INotifyPropertyChanged
{
    private bool _isRead;

    public bool IsRead
    {
        get { return _isRead; }
        set
        {
            _isRead = value;
            RaisePropertyChanged("IsRead");
        }
    }


    #region INotifyPropertyChanged Members

    /// <summary>
    /// Raised when a property on this object has a new value.
    /// </summary>
    public event PropertyChangedEventHandler PropertyChanged;

    #endregion

    /// <summary>
    /// Raises this object's PropertyChanged event.
    /// </summary>
    /// <param name="propertyName">The property that has a new value.</param>
    public virtual void RaisePropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            var e = new PropertyChangedEventArgs(propertyName);
            handler(this, e);
        }
    }
}