These are the steps I followed when re-writing my beloved Bloglines Blog Roll sidebar. I didn’t write it originally, but this is the second time I’ve re-written it, so I’ve become attached.

Step 1

Throw out the old component based sidebar. There’s very little code re-use. You might want to save the controller, but that’s it.

Step 2

Generate a rails plugin. This sets up a nice skeleton. I followed the convention of ending the plugin name with _sidebar. I don’t think it’s absolutely necessary. ruby script/generate plugin bloglines_sidebar

this will create a directory tree in vendor/plugins

create  vendor/plugins/bloglines_sidebar/lib
create  vendor/plugins/bloglines_sidebar/tasks
create  vendor/plugins/bloglines_sidebar/test
create  vendor/plugins/bloglines_sidebar/README
create  vendor/plugins/bloglines_sidebar/Rakefile
create  vendor/plugins/bloglines_sidebar/init.rb
create  vendor/plugins/bloglines_sidebar/install.rb
create  vendor/plugins/bloglines_sidebar/lib/bloglines_sidebar.rb
create  vendor/plugins/bloglines_sidebar/tasks/bloglines_sidebar_tasks.rake
create  vendor/plugins/bloglines_sidebar/test/bloglines_sidebar_test.rb

Step 3

Go to vendor/plugins/bloglines_sidebar

Step 4

Perform the magic that is necessary in init.rb.

NB: I should disclaim that I am no programmer, I am especially not a ruby programmer. There is stuff that I did, that I have no idea what, if anything, it does.

cat init.rb
require 'bloglines_sidebar'
BloglinesSidebar.view_root =  File.dirname(__FILE__) + '/views'

Step 5

go to the lib directory, and build up your sidebar controller.
In the old component sidebar there were two rhtml files to display, and they were called from a standard controller, with the typical 
class Foo
  def configure
  end
  def content
  end
end
style

This controlled:

1. How the sidebar configuration looked in the admin console.
2. How the sidebar looked in the pages.

Then all of the other work was done in the view.

Now, all of the configuration view stuff is done in the bloglines library, using the setting function.

My vendor/plugins/bloglines_sidebar/lib/bloglines_sidebar.rb looks like this:

The first six lines of the class set up the configuration. display_name and description are the same, then you just use setting function to do two things.

1. Set any default configuration.
2. Set up the html for the sidebar configuration.

My example doesn’t actually illustrate point 2 very well, but you can actually make each setting a different type of html form, like radio button. or text_area. I’ll put up an example here soon.

class BloglinesSidebar < Sidebar
  display_name "Bloglines" 
  description 'Display your Bloglines Blogroll in your sidebar'
  setting :title , nil, :label => 'Title'
  setting :user , nil, :label => 'User'
  setting :folder, nil, :label => 'Folder'
Then, all I have to do is setup a bloglines method that I can call from the view. This one is simple. Notice how folder and user are referenced from the settings above 
  def bloglines
    if folder.nil? || folder.empty?
      feed = "http://rpc.bloglines.com/blogroll?html=1&id=#{user}" 
    else
      feed = "http://rpc.bloglines.com/blogroll?html=1&id=#{user}&folder=#{folder}" 
    end
   open(feed).read
  end
end

Step 6

Now that we have the controller all set up, we can just add a view. Go back to `vendor/plaugins/bloglines_sidebar` and add a `views/` directory, then add a content.rhtml file with the following contents 
 
<h3><%= sidebar.title %></h3>
<%= sidebar.bloglines %>