c＃WPF DatePicker到标签绑定，以获取人员年龄

Question

My job is to bind a labels Content in XAML to a DatePicker, which is a persons birth date, to get their age. For example: Date picker: 2000.1.1 Label: 16. How do I do this?

edit

The label needs to change immediately when the DatePicker change.

Answer 1

Bind your label using an IValueConverter implementation such as the following:

class BirthdateToAgeConverter : IValueConverter
{
    public object Convert
        (
        object value,
        Type targetType,
        object parameter,
        string language)
    {
        var birthdate = ((DateTime) value).Date;
        var age = DateTime.Today.Year - birthdate.Year;

        if (birthdate > DateTime.Today.AddYears(-age))
        {
            age--;
        }
        return age;
    }

    public object ConvertBack
        (
        object value,
        Type targetType,
        object parameter,
        string language)
    {
        throw new NotImplementedException();
    }
}

Edit: In your XAML you need to define the binding path if you are binding directly to the DatePicker. You could also bind to SzuletesiDatum on your ViewModel.

<Label Content="{Binding ElementName=dtPicker, Path=SelectedDate ,Converter={StaticResource DTKC}}" 
       HorizontalAlignment="Left" Margin="356,94,0,0" 
       VerticalAlignment="Top"/> 
<DatePicker x:Name="dtPicker" 
            SelectedDate="{Binding SzuletesiDatum}" 
            HorizontalAlignment="Left" 
            Margin="112,94,0,0" 
            VerticalAlignment="Top"/>