Class: Rack::JSONP

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/jsonp.rb

Overview

A Rack middleware for providing JSON-P support.

Adapted from Flinn Mueller (actsasflinn.com/).

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ JSONP

Returns a new instance of JSONP.



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# File 'lib/rack/jsonp.rb', line 10

def initialize(app, options = {})
  @app = app
  @carriage_return = options[:carriage_return] || false
  @callback_param = options[:callback_param] || 'callback'
end

Instance Method Details

#call(env) ⇒ Object

Proxies the request to the application, stripping out the JSON-P callback method and padding the response with the appropriate callback format.

Changes nothing if no callback param is specified.



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# File 'lib/rack/jsonp.rb', line 21

def call(env)
  # remove the callback and _ parameters BEFORE calling the backend,
  # so that caching middleware does not store a copy for each value of the callback parameter
  request = Rack::Request.new(env)
  callback = request.params.delete(@callback_param)
  env['QUERY_STRING'] = env['QUERY_STRING'].split("&").delete_if{|param| param =~ /^(_|#{@callback_param})=/}.join("&")

  status, headers, response = @app.call(env)
  if callback && headers['Content-Type'] =~ /json/i
    response = pad(callback, response)
    headers['Content-Length'] = response.first.bytesize.to_s
    headers['Content-Type'] = 'application/javascript'
  elsif @carriage_return && headers['Content-Type'] =~ /json/i
    # add a \n after the response if this is a json (not JSONP) response
    response = carriage_return(response)
    headers['Content-Length'] = response.first.bytesize.to_s
  end
  [status, headers, response]
end

#carriage_return(response, body = "") ⇒ Object 



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# File 'lib/rack/jsonp.rb', line 53

def carriage_return(response, body = "")
  response.each{ |s| body << s.to_s }
  ["#{body}\n"]
end

#pad(callback, response, body = "") ⇒ Object

Pads the response with the appropriate callback format according to the JSON-P spec/requirements.

The Rack response spec indicates that it should be enumerable. The method of combining all of the data into a single string makes sense since JSON is returned as a full string.



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# File 'lib/rack/jsonp.rb', line 48

def pad(callback, response, body = "")
  response.each{ |s| body << s.to_s }
  ["#{callback}(#{body})"]
end