I couldn\'t find an elegant way for setting null values with a using AngularJS.
HTML :
You can use the ngOptions directive on the select. According to the documentation:
Optionally, a single hard-coded
element, with the value set to an empty string, can be nested into theelement. This element will then represent thenullor "not selected" option. See example below for demonstration.
It's obviously a better idea to define the options list directly in the controller.