问WPF ItemsControl ItemTemplate验证

EN

public class MyControl : UserControl
{
    public bool IsValid
    {
        get { return Validator.IsValid(MyDataGrid); }
    }
}

public static bool IsValid(DependencyObject parent)
{
    // Validate all the bindings on the parent
    bool valid = true;
    LocalValueEnumerator localValues = parent.GetLocalValueEnumerator();
    while (localValues.MoveNext())
    {
        LocalValueEntry entry = localValues.Current;
        if (BindingOperations.IsDataBound(parent, entry.Property))
        {
            Binding binding = BindingOperations.GetBinding(parent, entry.Property);
            foreach (ValidationRule rule in binding.ValidationRules)
            {
                ValidationResult result = rule.Validate(parent.GetValue(entry.Property), null);
                if (!result.IsValid)
                {
                    //BindingExpression expression = BindingOperations.GetBindingExpression(parent, entry.Property);
                    //System.Windows.Controls.Validation.MarkInvalid(expression, new ValidationError(rule, expression, result.ErrorContent, null));
                    //valid = false;
                    return false;
                }
            }
        }
    }

    // Validate all the bindings on the children
    for (int i = 0; i != VisualTreeHelper.GetChildrenCount(parent); ++i)
    {
        DependencyObject child = VisualTreeHelper.GetChild(parent, i);
        if (!IsValid(child))
        {
            //valid = false;
            return false;
        }
    }

    //return valid;
    return true;
}

public static bool IsValid(DependencyObject obj)
{
    // The dependency object is valid if it has no errors, 
    //and all of its children (that are dependency objects) are error-free.
    return !Validation.GetHasError(obj) &&
        GetVisualTreeChildren(obj)
        .OfType<DependencyObject>()
        .All(child => IsValid(child));
}

//VisualTreeHelper don't have a method to get all the children of a visual object
private static IEnumerable GetVisualTreeChildren(DependencyObject parent)
{
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        yield return VisualTreeHelper.GetChild(parent, i);
}