Why dont you use $resource out of the box features?
Here's a post example, with a simplified version of what you already have:
Resource service
factory('Article', function($resource) {
var Article = $resource('article/:id', {id: "@id"});
return Article;
});
Controller
var article = new Article();
article.startOffset = range.startOffset;
article.endOffset = range.endOffset;
article.$save();