How to customize to_json response in Rails 3

Question

I am using respond_with and everything is hooked up right to get data correctly. I want to customize the returned json, xml and

Answer 1

It is not the rails 3 built-in way, but I found a great gem that is actively maintained on Rails 3: acts_as_api

Answer 2

Probably too late, but I found a more DRY solution digging through the rails docs. This works in my brief tests, but may need some tweaking:

# This method overrides the default by forcing an :only option to be limited to entries in our
# PUBLIC_FIELDS list
def serializable_hash(options = nil)
  options ||= {}
  options[:only] ||= []
  options[:only] += PUBLIC_FIELDS
  options[:only].uniq!
  super(options)
end

This basically allows you to have a list of fields that are allowed for your public API, and you cannot accidentally expose the whole object. You can still expose specific fields manually, but by default your object is secure for .to_json, .to_xml, etc.

Answer 3

You can override as_json in your model. Something like:

class Post < ActiveRecord::Base
  def as_json(options = {})
    {
      attribute: self.attribute, # and so on for all you want to include
      images:    self.images,    # then do the same `as_json` method for Image
      foo:       self.really_cool_method
    }
  end
end

And Rails takes care of the rest when using respond_with. not entirely sure what options gets set to, but probably the options you give to respond_with (:include, :only and so on)