Question

I’m frequently building controllers where i would like multiple methods
(in addition to index, edit, show, etc.). Most of the time the actions i
desire could be lumped into show as they are simple GET operations,
however I don’t want to put too much logic in any one controller action.

Here is a quick example of two different ways to achieve the same
thing…

class TwitterFriendController < ApplicationController
  ## lump everything into show?
  def show
    if params[:id] == "follow"
      users = current_user.following
    elsif params[:id] == "follow_me"
      users = current_user.users_who_follow_me
    elsif params[:id] == "following_follow_me"
      users = current_user.following_who_follow_me
    elsif params[:id] == "following_who_do_not_follow_me"
      users = current_user.following_who_do_not_follow_me
    ...
    end
    respond_with do |format|
      format.json do {...}
    end
  end

  ## or split everything out into separate methods, this requires
additional routing
  def following
    ...
  end

  def users_who_follow_me
    ...
  end

  def following_who_follow_me
    ...
  end

  def following_who_do_not_follow_me
    ...
  end
end

Everything in show

• a ton of logic in one method
• DRY ? # lots of extra code needed for logic
• Less routing

Seperate Methods

• More routing
• not DRY
• Easy method lookup
• Easier to read individual methods

So again the real question is, which one of those techniques are less
bad.

Answer 1

I would do something like:

FOLLOW_WHITELIST = %w[ follow follow_me following_follow_me following_who_follow_me following_who_do_not_follow_me ]

def show
    if FOLLOW_WHITELIST.include? params[:id]
        users = current_user.send params[:id].to_sym
    end
    respond_with do |format|
        format.json do {...}
    end
end

This will call whatever method is passed in params[:id], as long as it’s in the whitelist (to prevent arbitrary code injection).

If having separate routes was a plus to you (nicer urls?), you could also dynamically generate the methods and routes with something like this:

class TwitterFriendController < ApplicationController

    FOLLOW_ACTIONS = %w[ follow follow_me following_follow_me following_who_follow_me following_who_do_not_follow_me ]

    FOLLOW_ACTIONS.each do |action|
        define_method action do
            users = current_user.send action.to_sym
            respond_with do |format|
              format.json do {...}
            end
        end
    end

end

And then in routes.rb:

FOLLOW_ACTIONS.each do |action|
    match action.to_sym => "controller##{action}"
end