Rails JSON API layouts with Jbuilder (or other)

Question

In my rails 3.2 app, I'm using jbuilder to render responses from my JSON api.

I want to provide a common structure to all API responses, and a layout would be the likely solution to keep my views DRY.

ex: I'd like every response to be of the following form :

{
  status: "ok|error|redirect",
  data:   { ... JSON specific to the current view ... },
  errors: [ ... ],
  notes:  [ ... ]
}

(where the value for data is a json structure provided by the view, everything else is from the layout)

However: I can't get the jbuilder layout yielding to the view correctly.

# in layout 
json.data yield

# in view
json.some "value"

results in:

{"data":"{\"some\":\"value\"}"}  # arg! my json has become a string

Trying things another way:

# in layout 
yield

# in view
json.data do |json|
  json.some "value"
end

results in :

{}

Has anyone had success doing this with jbuilder, or another json templating gem/method?

This juilder github issue suggests it's possible, but indicates others are having similar issues.

I see rabl (https://github.com/nesquena/rabl/) is supposed to support layouts (https://github.com/nesquena/rabl/wiki/Using-Layouts), but I've decided not to use it for other reasons (rabl makes complex json structures a nightmare, particularly when trying to control object roots etc).

Answer 1

I'll give you an alternative based on a solution we came up with:

# app/helpers/application_helper.rb
module ApplicationHelper
    def envelope(json, status, errors, notes)
        json.status status
        json.data do
            yield if block_given?
        end
        json.errors errors
        json.notes notes
    end
end

then, in the view, you can call envelope and include your json code like:

# app/views/api/v1/test/show.json.jbuilder
envelope(json, "OK" ) do
  json.some 'value'
end