WPF Replace value in TextBlock

Question

Lets say i have a TextBlock thats bound to a DateTime, is there any way to replace the value 0001-01-01 00:00:00 with an empty string?

Answer 1

Use a converter to format the date

Converter code :

public class MyDateConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {    
        DateTime dt = (DateTime)value;
        if (dt == dt.MinValue)
            return "";
        else
            return dt.ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {    
        string s = (string)value;
        if (string.IsNullOrEmpty(s))
            return DateTime.MinValue;
        else
            return DateTime.Parse(s);
    }
}

XAML :

...
<Window.Resources>
    <local:MyDateConverter x:Key="dateConverter"/>
</Window.Resources/>

...

<TextBlock Text="{Binding TheDate, Converter={StaticResource dateConverter}}"/>

Answer 2

You have a few options:

1. Bind to a DateTime? (that is, Nullable<DateTime>) rather than DateTime. Set the value to null when you want nothing to appear.
2. Bind to a separate property on your view model which is responsible for converting DateTime.MinValue to an empty string.
3. Bind directly to the DateTime property and use a converter to convert DateTime.MinValue to an empty string.

Example of #1

<TextBlock Text="{Binding SomeDateTime}"/>

public class YourViewModel : ViewModel
{
    private DateTime? _someDateTime;

    public DateTime? SomeDateTime
    {
        get { return _someDateTime; }
        set
        {
            if (_someDateTime != value)
            {
                _someDateTime = value;
                OnPropertyChanged("SomeDateTime");
            }
        }
    }
}

Example of #2

<TextBlock Text="{Binding SomeDateTimeString}"/>

public class YourViewModel : ViewModel
{
    private DateTime _someDateTime;

    public DateTime SomeDateTime
    {
        get { return _someDateTime; }
        set
        {
            if (_someDateTime != value)
            {
                _someDateTime = value;
                OnPropertyChanged("SomeDateTime");
                OnPropertyChanged("SomeDateTimeString");
            }
        }
    }

    public string SomeDateTimeString
    {
        get { return SomeDateTime == DateTime.MinValue ? "" : SomeDateTime; }
    }
}

Example of #3

<!-- in resources -->
<local:DateTimeConverter x:Key="YourConverter"/>

<TextBlock Text="{Binding SomeDateTime, Converter={StaticResource YourConverter}}"/>

public class YourClass
{
    private DateTime _someDateTime;

    public DateTime SomeDateTime
    {
        get { return _someDateTime; }
        set
        {
            if (_someDateTime != value)
            {
                _someDateTime = value;
                OnPropertyChanged("SomeDateTime");
            }
        }
    }
}

public class DateTimeConverter : IValueConverter
{
    public object Convert(object value ...)
    {
        return value == DateTime.MinValue ? "" : value;
    }

    ...
}

HTH, Kent