It’s great to give birth to a child, release it into the world, and see it go on to do great things that you wouldn’t have thought of.

I hope my wife doesn’t read this and get any ideas, because I’m actually talking about Gruff and Bellygraph. You can sign up for an account that lets you plot your data with your choice of colors, then post the resulting awesome graphs on your own site.

Speaking of which, patches have been submitted and I’m about to issue a release of Gruff that supports negative numbers, has better scaling if your data points don’t start at zero, and uses more consistent color/data mapping.

RJS

In yet another attempt to improve my efficiency and keep track of my time, I wrote a Rails app that uses the principles of the Printable CEO ™. This time I used 100% Markaby and the RJS Plugin. I hope to make it publicly available in a week or two.

RJS is a feature of the upcoming Rails 1.1 that makes it easy to send Ajax responses back as JavaScript (implemented by the dynamic duo). You can make individual calls to different elements, or send entire rendered view templates.

RJS has been applauded as an easy way to update multiple elements on a page, but I think it also fits into the flow of a web request a lot better.

I’m using observe_form to monitor changes to the task forms so you never have to hit “Submit.” By using RJS, I can create the task on the server and then send back Javascript that fires a form observer using the appropriate ID. If it was done with form_remote_tag :complete => ..., I wouldn’t know the ID and would have to start the observer in a more complicated way.

Content-Type Header

The bug that I had to fix also revealed a little bit about how RJS works. In order to fix a bug with Safari and Ajax, I was using a before_filter to set the Content-Type header to ‘text/html; charset=utf-8’ (as mentioned on the Rails Wiki). But this broke RJS. The Javascript was received, but never executed by the browser.

The solution?

The browser was getting a header like this

Content-Type: text/html; charset=utf-8

but it needs to see this

Content-Type: text/javascript; charset=utf-8

The solution was to change the before_filter to an after_filter (so Rails can set the Content-Type first, based on the actual template that was rendered). I only send the extra charset if text is being sent (some actions render a graphic image).

after_filter :set_charset

def set_charset
  content_type = @headers["Content-Type"] || 'text/html'
  if /^text\//.match(content_type)
    @headers["Content-Type"] = "#{content_type}; charset=utf-8" 
  end
end

This wouldn’t be complete without one of the functional tests that helped me debug this:

def test_rjs_header
  get :make_some_rjs, :id => 1
  assert_match @response.headers['Content-Type'], 'text/javascript; charset=utf-8'
end

def test_generated_graphic
  get :make_a_graphic, :id => 1
  assert_match @response.headers['Content-Type'], 'image/png'
  assert_match @response.headers['Content-Disposition'], %q{inline; filename="1.png"}
end

According to the Printable CEO, I get 2 points for writing a blog article. It’s time to score some more points!