title: Backbone doing POST request instead of PUT request
body: <p>I am trying to set a model's attribute to be something different. When I save the model, Backbone issues a POST request instead of a PUT request.</p>
  
  <p>I read on another Stackoverflow post that Backbone uses a model's id to determine if a model is new or not. When I <code>console.log(model)</code>, the model has an id attribute. When I <code>console.log(model.id)</code>, it prints out undefined. How come when I do a <code>console.log(model)</code>, the model has a id attribute, yet when I do <code>console.log(model.id)</code>, I get back undefined?</p>
  
  <p>Which way does Backbone use to determine if a model is new or not? And, how can I fix the problem? I am using backbone-tastypie.</p>