This post originated from an RSS feed registered with Ruby Buzz by Obie Fernandez. Original Post: render :text gotcha Feed Title: Obie On Rails (Has It Been 9 Years Already?) Feed URL: http://jroller.com/obie/feed/entries/rss Feed Description: Obie Fernandez talks about life as a technologist, mostly as ramblings about software development and consulting. Nowadays it's pretty much all about Ruby and Ruby on Rails. Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Obie Fernandez Latest Posts From Obie On Rails (Has It Been 9 Years Already?)

Hi everyone! Hope you're all having a nice holiday season and I wish you a great new year. This morning I diagnosed a production issue that I think qualifies as a gotcha and which probably affects more than a few Rails apps out there. The gotcha has to do with proper use of render :text in controller actions, used to send plain-text as the response back to the browser. It doesn't work with nil!

In ActionController::Base, in a big if/else statement inside the render method, the following conditional is used to determine whether to trigger text rendering:

if text = options[:text]
  render_for_text(text, options[:status])

If you're passing render :text the result of a method call (for instance, an object attribute) and it gets a nil, the render handling code in Rails is going to drop right down to the default rendering behavior, which is to try to render what was passed to it as a file:

else
  render_file(default_template_name, options[:status], true)

Of course, if you didn't intend for that to happen, you're probably going to end up with an error, specifically Missing template [RAILS_ROOT]/vendor/rails/actionpack/lib/action_controller/base.rb:1242:in `assert_existence_of_template_file'.

The most notable use of render :text in the Rails codebase itself is the in_place_edit functionality, which is an official plugin in Rails 2. It handles this gotcha by calling to_s on the result of the method call:

def in_place_edit_for(object, attribute, options = {})
  define_method("set_#{object}_#{attribute}") do
    @item = object.to_s.camelize.constantize.find(params[:id])
    @item.update_attribute(attribute, params[:value])
    render :text => @item.send(attribute).to_s
  end
end