Category: Ruby

The Rails PDF plugin is a dandy little thing. It wraps the PDF::Writer library for Ruby, allowing PDF templates to be defined like any other Rails view (with a .rpdf extension, of course).

One thing it doesn’t do is allow access to the parent controller’s helper from within a PDF template. It’s easy enough to patch the plugin to accomplish this, though.

First, open up vendor/plugins/railspdf/lib/railspdf.rb and take a gander. This is the section we’re interested in:

...
class PDFRender < ActionView::Base
  def initialize(action_view)
    @action_view = action_view
  end
  ...

PDF templates get rendered in the context of this class. All we need to do to gain access to the controller's helper here is include the helper from inside the class initializer, like so:

...
class PDFRender < ActionView::Base
  def initialize(action_view)
    @action_view = action_view
    prefix = action_view.controller.class.to_s.gsub(/Controller/, '')
    self.class.send(:include, "#{prefix}Helper".constantize)
  end
  ...

We first calculate the prefix of the helper based on the class of the controller assigned to the view. Then we include the helper in the current class by constantizing the resulting string.

We're almost done. Since ApplicationHelper should be available to every controller and helper in the system, let's include it here for good measure:

...
class PDFRender < ActionView::Base
  include ApplicationHelper
  
  def initialize(action_view)
    @action_view = action_view
    prefix = action_view.controller.class.to_s.gsub(/Controller/, '')
    self.class.send(:include, "#{prefix}Helper".constantize)
  end
  ...

And we're done! Piece of cake. Now we can reference methods from inside our controller's helper. We can, of course, modify this hack somewhat so that the same helper (something like "PdfHelper" maybe) is included for all of our templates. This enables us to isolate our PDF-specific helper methods in a single module.

And before you ask, yes, it's nasty to be modifying the plugin directly. There is a way to inject this patch into the PDFRender class without touching anything in the plugin... but I've gotta leave something for you to figure out! :)

If you were one of the unfortunate souls who missed RailsConf this year, I’m sorry for you. If you happened to be at RailsConf but missed Justin Gehtland’s excellent Streamlined tutorial then you are truly of all people most pitiable.

On a more serious note, the tutorial was very good and has sparked a lot of interesting ideas for further enhancing Streamlined beyond its already hefty feature set. For those who don’t know, Streamlined is a Rails plugin that brings the declarative goodness of ActiveRecord to the UI. It enhances your views with full-featured scaffolds that include relationship management, quick adding of associated models, and much more.

If you haven’t played with Streamlined before, why not give it a try? With several fresh screencasts over at the blog, a bundle of new documentation, a new sample project, and version 1.0 on the horizon… there’s no time like the present.

Getting started with Streamlined is easy…

(more…)