Resource Fu

ResourceFu is a collection of hacks from various plugins that I’ve developed to make using nested and polymorphic resources simpler in my projects.

Refactoring all of the hacks into a cohesive unit is still a work-in-progress so bear with me.

The first part that I’ve pulled in is:

Inferencing url helper methods:

Assuming this routes.rb setup:

map.resources :artists do |artist| artist.resources :albums do |album| album.resources :songs end end

The standard resource helpers generated for ‘albums’ require that you always specify the artist_id:

album_path(@artist, @album)

And, if you want to have additional parameters (such as a :page number when paginating) you can’t use the positional arguments form (above) when calling the url helper, you have to use a hash for everything:

album_path(:artist_id => @artist, :id => @album, :page => 2)

Also, the standard resource helpers fill in the route by processing your positional arguments from left-to-right.

album_path(@album) == album_path(:artist_id => @album) # ACK!

ResourceFu changes the way url helpers behave – and it does it in a way that avoids costly per-request evals and/or route re-recognition.

With ResourceFu your positional arguments are ‘anchored’ on the right of the route: which means that if your route has three segments and you only supply two positional arguments, the url helper assumes you are supplying the last two segments.

Using the above example of artists, albums and songs:

song_path(@album, @song) == song_path(:album_id => @album, :id => @song)

However, the route for song_path is still missing a critical piece of information, namely the artist_id.

ResourceFu tries to ‘guess’ that value with a simple convention:

Any route segments that are missing are filled in by looking for instance variables with a relevant name. So in the example:

song_path(@album, @song)

ResourceFu will try to set the :artist_id param by first looking for an instance variable called @artist and then falling back to looking for an instance variable called @artist_id.

In album_controller.rb:

def show @artist_id = params[:artist_id] # or fetch the actual Artist if you want @album = Album.find(params[:id], :conditions => {:artist_id => @artist_id}) @album.songs.each do |song| song_path(song) #=> /artists/@artist_id/albums/@album.id/songs/song.id end end

Finally, if you want additional, non-route-segment params, you don’t have to completely switch to the hash-argument style for route helpers:

song_path(@artist, @album, @song, :page => 2, :per_page => 20)

NOTE: This description has been extracted from the Plugin README and so the formatting may need updating to make browser friendly