How to parse JSON request body in Sinatra just once and expose it to all routes?

Question

I am writing an API and it receives a JSON payload as the request body.

To get at it currently, I am doing something like this:

post \'/doSomething\'         


        

Answer 1

You can also use Rack Middleware to parse it. See https://github.com/rack/rack-contrib Just use Rack::PostBodyContentTypeParser when initializing your Sinatra class.

Answer 2

before do
  request.body.rewind
  @request_payload = JSON.parse(request.body.read, symbolize_names: true)
end

So you can also symbolize_names while parsing JSON request body, this will give you access to your nested params like this @request_payload[:user]

Answer 3

You can parse your JSON post body as a Hash with Rack::PostBodyContentTypeParser from https://github.com/rack/rack-contrib:

require 'rack/contrib/post_body_content_type_parser'

class Api < Sinatra::Application
  use Rack::PostBodyContentTypeParser
  ...
end

You can even pass a custom block to Rack::PostBodyContentTypeParser to parse the JSON as symbols instead of strings:

a_proc = proc { |body| JSON.parse(body, symbolize_names: true, create_additions: false) }
use Rack::PostBodyContentTypeParser, &a_proc

Answer 4

Like this working for sinatra 1.4.5

before do
  if request.body.size > 0
    request.body.rewind
    @params = ActiveSupport::JSON.decode(request.body.read)
  end
end

Answer 5

Use a sinatra before handler:

before do
  request.body.rewind
  @request_payload = JSON.parse request.body.read
end

this will expose it to the current request handler. If you want it exposed to all handlers, put it in a superclass and extend that class in your handlers.