How to write a dynamic route in Rails 3?

Question

I'm trying to write a generic route that will allow me to refer to it by the controller's action.

I'm using the following line:

  match ':action' => 'pages#:action', :as => 'action'

let's say an action named `foobar' in the pages controller. I'd like to be able to write

link_to 'Click Me', pages_foobar_path

in a view. The problem is that I get the error Invalid route name: ':action' when I try to write that route.

Mind you, the line

match ':action' => 'pages#:action'

without the :as parameter works perfectly, but then I have to manually write the path, as such:

link_to 'Click Me', '/pages/foobar'

any way around that?

Answer 1

If dynamic means "recognize my actions when Rails starts up and generate routes dynamically":

It's not something that I would do, but it does what you want it to do without any redirection nor method_missing runtime overhead.

In config/routes.rb

controller_filenames = Dir.new("#{Rails.root}/app/controllers").entries
controller_filenames.each do |filename|
  # you could restrict to only the pages_controller.rb on the next line,
  # and in that case, you could simplify even more (see next example)...
  if filename =~ /_controller\.rb$/
    controller_name = filename.sub(/.rb$/, "")
    controller_route_name = controller_name.sub(/_controller$/, "")
    controller = controller_name.camelize.constantize.new
    controller.action_methods.each do |action|
      # if you don't want the controller name in your path match, just omit it...
      match "#{controller_route_name}/#{action}" => "#{controller_route_name}##{action}", :as => "#{controller_route_name}_#{action}"
    end
  end
end

If you only want to do this for your pages_controller.rb file, then:

controller_name = "pages_controller"
controller_route_name = "pages"
controller = controller_name.camelize.constantize.new
controller.action_methods.each do |action|
  # I've removed the controller_route_name from the match here...
  match "#{action}" => "#{controller_route_name}##{action}", :as => "#{controller_route_name}_#{action}"
end

Now, if dynamic means "generate a route whenever I dynamically generate a new action":

You could really play with fire. Any of your existing actions can define new actions and routes. For example, I could define a route in config/routes.rb (but this could be any existing route):

match '/dynamic_define' => 'application#dynamic_define'

Couple that with a method in ApplicationController (again, this could be any existing action):

def dynamic_define
  method_name = params[:mname]
  self.class.send(:define_method, method_name) {
    render :text => "output from #{method_name}"
  }
  Rails.application.routes.disable_clear_and_finalize = true
  Rails.application.routes.draw do
    match "/#{method_name}" => "application##{method_name}", :as => "application_#{method_name}"
  end
  render :text => "dynamic_define just created a new action named #{method_name}"
end

In your browser, you can visit:

/dynamic_define?mname=my_new_dynamic_action
# browser renders "dynamic_define just created a new action named my_new_dynamic_action"

And then visit:

/my_new_dynamic_action
# browser renders "output from my_new_dynamic_action"

Answer 2

I think you can get as far as:

link_to 'Click me', pages_path(:action)

by redirecting

match ':action' => 'pages#:action'
match '/pages/:action' => redirect(":action") # pages_path(:action) will match

This is less typing than the approach suggested in the first answer, but seems less expressive if anything.

I suppose you could override method_missing in your view class to catch pages_[stuff]_path and generate the proper string, e.g.

def method_missing(name, *args, &block)
  if name =~ /^pages_[a-z]*_path$/
    "/#{name.to_s.gsub!(/^pages_/,'').gsub!(/_path$/,'')}"
  else
    super
  end
end

Forgive me if my method_missing knowledge or regex capabilities are lacking - hopefully this is helpful directionally at least.