CODEWITHSUNDEEP
rubysinatrarack
lmirosevic
lmirosevic

Reputation: 16317

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

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' do
    request.body.rewind
    request_payload = JSON.parse request.body.read

    #do something with request_payload
    body request_payload['someKey']
end

What's a good way to abstract this away so that I don't need to do it for each route? Some of my routes are more complicated than this, and as a result the request.body would get reread and reparsed several times per route with this approach, which I want to avoid.

Is there some way to make the request_payload just magically available to routes? Like this:

post '/doSomething' do
    #do something with request_payload, it's already parsed and available
    body request_payload['someKey']
end

Upvotes: 46

Views: 44076

Answers (5)

Pere Joan Martorell
Pere Joan Martorell

Reputation: 3152

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

Upvotes: 3

Serj Petrenko
Serj Petrenko

Reputation: 101

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]

Upvotes: 3

Harper Maddox
Harper Maddox

Reputation: 550

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.

Upvotes: 12

Pavel Evstigneev
Pavel Evstigneev

Reputation: 5126

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

Upvotes: 6

mcfinnigan
mcfinnigan

Reputation: 11638

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.

Upvotes: 73

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