add: `belongs_to :user` in the post model to make this work. Also make the same in the json. It will output a dump of the user obejct. to make the default field `email` when converting to string use:
```
  def to_s; email end
```
you can add `to_s` and `to_param` to each model - the second one is used for when the object is used by the routes. You will need it in the next pull requests.