Refactor this controller? - ruby-on-rails-3

Question

class ArticlesController < ApplicationController
def index
#articles = Article.by_popularity
if params[:category] == 'popular'
#articles = #articles.by_popularity
end
if params[:category] == 'recent'
#articles = #articles.by_recent
end
if params[:category] == 'local'
index_by_local and return
end
if params[:genre]
index_by_genre and return
end
respond_to do |format|
format.html # index.html.erb
format.xml { render :xml => #articles }
end
end
def index_by_local
# 10 lines of code here
render :template => 'articles/index_by_local'
end
def index_by_genre
# ANOTHER 10 lines of code here
render :template => 'articles/index_by_genre'
end
end
As you can see from above. My controller is not exactly thin. What its doing is, depending on the params that were passed, it interacts with the model to filter out records.
And if params[:local] or params[:genre] was passed. Then it calls its own methods respectively (def index_by_local and def index_by_genre) to do further processing. These methods also load their own template, instead of index.html.erb.
Is this quite typical for a controller to look? Or should I be refactoring this somehow?

Answer 1

We can move the first few lines into the model(article.rb):
def get_by_category(category)
# Return articles based on the category.
end
In this way we can completely test the article fetching logic using unit tests.
In general move all the code related to fetching records inside model.
Controllers in general
should authorize the user
get records using the params and assign them to instance variables
[These must typically be function
calls to model]
Render or redirect

Answer 2

I would define scopes for each of the collections you want to use.
class Article < ActiveRecord::Base
...
scope :popular, where("articles.popular = ?", true) # or whatever you need
scope :recent, where(...)
scope :by_genre, where(...)
scope :local, where(...)
...
def self.filtered(filter)
case filter
when 'popular'
Article.popular, 'articles/index'
when 'recent'
Article.recent, 'articles/index'
when 'genre'
Article.by_genre, 'articles/index_by_genre'
when 'local'
Article.local, 'articles/index_by_local'
else
raise "Unknown Filter"
end
end
end
Then in your controller action, something like this:
def index
#articles, template = Article.filtered(params[:category] || params[:genre])
respond_to do |format|
format.html { render :template => template }
format.xml { render :xml => #articles }
end
end