使用MVVM模式从视图模型到WPF中的视图的条件绑定

I am developing a WPF application using MVVM pattern. I have a combo in the view and two lists in the viewmodel (projects and organizations). Depending on the organizations list items I have to bind the the name of the organization or not. For example if the Count property of the organizations list is 1 the combobox item have to be I am developing a WPF application using MVVM pa