If resource.userId === 0

$resource('/users/:userId/', {}, {save: {method: 'POST'}}).$save() 

calls the wrong url '/users' instead of '/users/0' since userId === 0 is treated as false during uri segment encoding.

I believe it should be checked agains 'undefined' and null instead.

Version 1.0.1
File: angular-resource.js (292)
encodedVal = encodeUriSegment(params[urlParam] || self.defaults[urlParam] || "");