[ruby-on-rails] How to redirect to previous page in Ruby On Rails?

I have a page that lists all of the projects that has sortable headers and pagination.

path:
/projects?order=asc&page=3&sort=code

I choose to edit one of the projects

path:
projects/436/edit

When I click save on that page, it calls the projects controller / update method. After I update the code I want to redirect to the path that I was on before I clicked edit a specific project. In other words, I want to be on the same page with the same sorting.

I saw link_to(:back) and thought that :back may work in redirect_to(:back), but that's a no go.

puts YAML::dump(:back) 
yields the following:
:back 

Any ideas on How I could get this to work. It seems like a problem that would be easily solved, but I'm new to RoR.

request.referer is set by Rack and is set as follows:

def referer
  @env['HTTP_REFERER'] || '/'
end

Just do a redirect_to request.referer and it will always redirect to the true referring page, or the root_path ('/'). This is essential when passing tests that fail in cases of direct-nav to a particular page in which the controller throws a redirect_to :back

I like Jaime's method with one exception, it worked better for me to re-store the referer every time:

def edit
    session[:return_to] = request.referer
...

The reason is that if you edit multiple objects, you will always be redirected back to the first URL you stored in the session with Jaime's method. For example, let's say I have objects Apple and Orange. I edit Apple and session[:return_to] gets set to the referer of that action. When I go to edit Oranges using the same code, session[:return_to] will not get set because it is already defined. So when I update the Orange, I will get sent to the referer of the previous Apple#edit action.

This is how we do it in our application

def store_location
  session[:return_to] = request.fullpath if request.get? and controller_name != "user_sessions" and controller_name != "sessions"
end

def redirect_back_or_default(default)
  redirect_to(session[:return_to] || default)
end

This way you only store last GET request in :return_to session param, so all forms, even when multiple time POSTed would work with :return_to.

In rails 5, as per the instructions in Rails Guides, you can use:

redirect_back(fallback_location: root_path)

The 'back' location is pulled from the HTTP_REFERER header which is not guaranteed to be set by the browser. Thats why you should provide a 'fallback_location'.

Why does redirect_to(:back) not work for you, why is it a no go?

redirect_to(:back) works like a charm for me. It's just a short cut for redirect_to(request.env['HTTP_REFERER'])

http://apidock.com/rails/ActionController/Base/redirect_to (pre Rails 3) or http://apidock.com/rails/ActionController/Redirecting/redirect_to (Rails 3)

Please note that redirect_to(:back) is being deprecated in Rails 5. You can use

redirect_back(fallback_location: 'something') instead (see http://blog.bigbinary.com/2016/02/29/rails-5-improves-redirect_to_back-with-redirect-back.html)

For those who are interested, here is my implementation extending MBO's original answer (written against rails 4.2.4, ruby 2.1.5).

class ApplicationController < ActionController::Base
  after_filter :set_return_to_location

  REDIRECT_CONTROLLER_BLACKLIST = %w(
    sessions
    user_sessions
    ...
    etc.
  )

  ...

  def set_return_to_location
    return unless request.get?
    return unless request.format.html?
    return unless %w(show index edit).include?(params[:action])
    return if REDIRECT_CONTROLLER_BLACKLIST.include?(controller_name)
    session[:return_to] = request.fullpath
  end

  def redirect_back_or_default(default_path = root_path)
    redirect_to(
      session[:return_to].present? && session[:return_to] != request.fullpath ?
        session[:return_to] : default_path
    )
  end
end