How do I access the value of a boolean property on a JSON object generated by Rails in an AngularJS expression?

The scenario:

I was using the ng-class directive on an element that had an ng-repeat directive. I put the ng-class on my element to add a class to my element if some conditions were met. The problem I encountered was with my conditions. Since they had come from some JSON that I had generated with Ruby on Rails, the keys in my JSON that returned booleans ended with question marks. When quoted, question marks are perfectly valid in JSON keys, but when I tried to access them in my AngularJS expression using dot-notation, the console in Chrome would show an error:

The failing code:

<tr ng-repeat="foo in bars" ng-class="{'boo': foo.bar.baz? || !foo.bar.yes? }">

The error:

Error: Lexer Error: Unexpected next character  at columns 39-39 [?] in expression