Restangular error handling results in CORS issue? - angularjs

Question

We're having an issue with restangular and handling errors from the API. If the API responds with a 200, then everything works perfectly. However, when the API returns a 409 we receive a lovely:
XMLHttpRequest cannot load https://**token=*. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://127.0.0.1:9000' is therefore not allowed access.
Response headers from a valid post operation:
Access-Control-Allow-Credentials:true
Access-Control-Allow-Headers:Origin, X-Requested-With, Content-Type, Authorization, Accept, X-Authorization, User-Agent, DNT, Cache-Control, X-Mx-ReqToken, Keep-Alive, If-Modified-Since
Access-Control-Allow-Methods:GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Origin:http://127.0.0.1:9000
Access-Control-Max-Age:1728000
Cache-Control:private, must-revalidate
Connection:keep-alive
Content-Type:text/html; charset=utf-8
Date:Fri, 29 Aug 2014 21:55:51 GMT
ETag:"*****"
Server:nginx/1.6.0
X-Frame-Options:SAMEORIGIN
X-Powered-By:HHVM/3.3.0-dev+2014.08.22
Response headers from a post operation with a 409 response captured from postman:
Cache-Control →no-cache
Connection →keep-alive
Content-Encoding →gzip
Content-Type →text/html; charset=utf-8
Date →Fri, 29 Aug 2014 21:56:59 GMT
Server →nginx/1.6.0
Transfer-Encoding →chunked
X-Frame-Options →SAMEORIGIN
X-Powered-By →HHVM/3.3.0-dev+2014.08.22
Any attempt to catch the response.status or error handling as outlined in the
restangular docs results in this:
config: Object
data: ""
headers: function (name) {
status: 0
statusText: ""
I always have a status of 0.
Let me know if you need to see any additional information.

Answer 1

This really has nothing to do with restangular but with your webserver config.
What is happening is that your webserver isn't set up to return the CORS headers in case an error occurs.
Because of this you can not access any of the returned data from the ajax request, even tough data was actually returned. You won't even be able to see it in chrome's network inspector ( except for the status code and headers ). Additionally, because this is a security violation, you can't even access the status code, headers or anything from javascript everything is being blocked.
You will however be able to see it in a proxy like fiddler or charles, or when you make the request directly to the api server ( in case of a GET request ), because a request was actually made and data will have been returned, the browsers security policies just denies access to it trough AJAX because of the missing CORS headers.
This doesn't mean you can just fire off ajax requests to any other domain and possibly interact with it. The only reason your requests are going trough in the first place is because the preflight OPTION request is set up to allow CORS
Solution:
Set up your WebServer to include CORS headers in case an error response is generated, the headers you are looking for are all available in the valid response you supplied ( Access-Control-* ).