如何将IValueConverter添加到现有的Binding中

Question

I have a TextBox and I try to add an IValueConverter to the TextProperty-Binding in code behind.

        var bindingExpression = TextBox.GetBindingExpression(TextBox.TextProperty);
        if (bindingExpression != null && bindingExpression.ParentBinding.Converter == null)
        {
            bindingExpression.ParentBinding.Converter = new MyConverter();
        }

In this step the following exception throws: Binding cannot be changed after it has been used. How can I access the binding earlier to change the property?

Answer 1

1. Create new Binding and apply it. You can get various properties from old Binding instance.

   or,

2. Use Trigger to apply conditional Binding , one with and another without IValueConverter .