Reponse headers not available in success callback

[brianberlin]

i'm having an issue getting a header in ampersand-rest-collection success callback after updating to v5.0.0.

http://cl.ly/image/011Y1q1Y3s1g

[dhritzkiv]

You may have figured it out by now, but to answer your question:

xhr in this case is the browser default return value for an XMLHttpRequest instance. This is returned by calling view.collection.fetch(). In order to retrieve headers from an XHR instance, you need to call xhr.getAllResponseHeaders() (or xhr.getResponseHeader(header) to get a specific header.)

However, more conveniently, in your success callback, the last argument, the response object, has those headers pre-populated for you. So in order to access the count header you could do this:

view.collection.fetch({
    success: function(collection, json, response) {
        var count = response.headers.count;
    }
});