Question

I’m using AMCharts and rails. AMCharts uses the Image Magic lib to export an image of the chart. In rails this is done with the gem, RMagic.

In a controller this is implemented with the following controller method:

  def export
    width = params[:width].to_i
    height = params[:height].to_i
    data = {}
    img = Magick::Image.new(width, height)
    height.times do |y|
      row = params["r#{y}"].split(',')
      row.size.times do |r|
        pixel = row[r].to_s.split(':')
        pixel[0] = pixel[0].to_s.rjust(6, '0')
        if pixel.size == 2
          pixel[1].to_i.times do
            (data[y] ||= []) << pixel[0]
          end
        else
          (data[y] ||= []) << pixel[0]
        end
      end
      width.times do |x|
        img.pixel_color(x, y, "##{data[y][x]}")
      end
    end
    img.format = "PNG"
    send_data(img.to_blob , :disposition => 'inline', :type => 'image/png', :filename => "chart.png?#{rand(99999999).to_i}")
  end

When the controller is accessed however, I receive this error in the page:

The change you wanted was rejected.

Maybe you tried to change something you didn't have access to.

And this error in the logs (its running on heroku btw):

    ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken):
  /home/heroku_rack/lib/static_assets.rb:9:in `call'
  /home/heroku_rack/lib/last_access.rb:25:in `call'
  /home/heroku_rack/lib/date_header.rb:14:in `call'
  thin (1.0.1) lib/thin/connection.rb:80:in `pre_process'
  thin (1.0.1) lib/thin/connection.rb:78:in `catch'
  thin (1.0.1) lib/thin/connection.rb:78:in `pre_process'
  thin (1.0.1) lib/thin/connection.rb:57:in `process'
  thin (1.0.1) lib/thin/connection.rb:42:in `receive_data'
  eventmachine (0.12.6) lib/eventmachine.rb:240:in `run_machine'
  eventmachine (0.12.6) lib/eventmachine.rb:240:in `run'
  thin (1.0.1) lib/thin/backends/base.rb:57:in `start'
  thin (1.0.1) lib/thin/server.rb:150:in `start'
  thin (1.0.1) lib/thin/controllers/controller.rb:80:in `start'
  thin (1.0.1) lib/thin/runner.rb:173:in `send'
  thin (1.0.1) lib/thin/runner.rb:173:in `run_command'
  thin (1.0.1) lib/thin/runner.rb:139:in `run!'
  thin (1.0.1) bin/thin:6
  /usr/local/bin/thin:20:in `load'
  /usr/local/bin/thin:20

Rendering /disk1/home/slugs/149903_609c236_eb4f/mnt/public/422.html (422 Unprocessable Entity)

Anyone have any idea what’s going on here?

Answer 1

I’ve figured it out:

added: require ‘RMagick’

&

skip_before_filter :verify_authenticity_token

to my class