Technical Pickles

After entering the loving embrace of named routes, I found myself with the following routes:

map.posts_by_tag 'blog/by_tag/:tag', :controller => 'blog', :action => 'by_tag'
map.connect 'blog/by_tag/:tag.:format', :controller => 'blog', :action => 'by_tag'
map.post_tags 'blog/tags', :controller => 'blog', :action => 'tags'
map.all_posts 'blog/all', :controller => 'blog', :action => 'all'
map.permalink 'blog/permalink/:permalink', :controller => 'blog',
  :action => 'permalink'
map.connect 'blog/permalink/:permalink.:format', :controller => 'blog',
  :action => 'permalink', :format => nil

Yick. Seems like there's a bit of repeated code here. Fortunate for us, Ruby does have mechanisms for dealing with this, with_options. Essentially, it does some magic, such that you give it some options, and inside the block you provide it, you're able to indicate you want ot use those options in addition to any other options you may need. That's a bit wordy, so let the code speak for itself:

map.with_options :controller => 'blog' do |blog|
  blog.with_options :action => 'by_tag' do |blog_by_tag|
    blog_by_tag.posts_by_tag 'blog/by_tag/:tag'
    blog_by_tag.connect 'blog/by_tag/:tag.:format'
  end
  blog.with_options :action => 'permalink' do |blog_permalink|
    blog_permalink.permalink 'blog/permalink/:permalink.:format'
    blog_permalink.connect 'blog/permalink/:permalink'
  end
  blog.post_tags 'blog/tags.:format', :action => 'tags'
  blog.all_posts 'blog/all.:format', :action => 'all'
end

The resulting code minimizes repetition, and also illustrates the intent much more clearly.

In my last installment, I added a tag listing. For this listing, we links that look like:

<%= link_to tag.name, {:controller => 'blog', :action => 'by_tag',
  :tag => tag.name} %>

With a little work, we can refactor this to:

<%= link_to tag.name, posts_by_tag_url(:tag => tag.name) %>

posts_by_tag_url!?! You may be boggled by this. It's pretty easy actually. When you're defining your routes, you can choose to give it a name, instead of the normal 'anonymous' routes.

Here's an anonymous route:

map.connect 'blog/by_tag/:tag' :controller => 'blog',
  :action => 'by_tag'

Here's the equivalent named route:

map.posts_by_tag 'blog/by_tag/:tag' :controller => 'blog',
  :action => 'by_tag'

The advantage of using named routes is that it provides you some abstraction over the specific controller/action being used in the link. For example, before I refactored tags to by_tag, I may have had a link that looked like:

<%= link_to tag_name, :controller => 'blog', :action => 'tags',
  :tag => tag_name %>

As soon as I changed this to by_tag, I needed to fix this, and everywhere it occurs. If I had been using the named route, it wouldn't have been an issued.