Question

I have an “Id” dependency property declared:

    public long Id
    {
        get { return (long)GetValue(IdProperty); }
        set { SetValue(IdProperty, value); }
    }
    public static readonly DependencyProperty IdProperty =
        DependencyProperty.Register("Id", typeof(long),
        typeof(Component), new PropertyMetadata(-1));

“Component” is a User Control that have “Id”.

When I run the application it gives me an exeption:

An unhandled exception of type ‘System.TypeInitializationException’ occurred in PresentationCore.dll

Additional information: The type initializer for ‘My_Program.Component’ threw an exception.

If i change the type “long” to “int” everything works fine.
What is the problem? can’t I create a dependency property of type “long”?

Thank you for your help.

Answer 1

Try casting the default value to long:

new PropertyMetadata((long)-1);