How to get segment keys from a Rails 3 route?

Question

I need to determine the number of route segment keys in the current path for an application I'm working on, and despite digging around for a bit in the related Rails 3 source files, I can't figure it out.

I know how to use url_for and request to build a path from the current route, but I don't know how to actually get to the ActionController::Routing::Route that maps to the route url_for is using. If I can get an instance of the route I need, I can just call Route#segment_keys and get what I need.

If anybody is interested, the reason I'm doing this is so I can toggle between resources with a select dropdown and stay on the current view that applies to the currently selected resource, but only if the current path doesn't contain nested paths (i.e. toggle /resources/1/edit to /resources/2/edit but do not toggle between /resources/1/subresources/1 to /resources/2/subresources/1 because subresource number 1 is not a child of resource 2).

Whats your model structure? http://guides.rubyonrails.org/ explains all this. — jvatic, Apr 16 '11 at 01:44
@jvatic What do the models have to do with getting the number of route segments for a given route? And where in the Guides is this? I'll gladly read up on it there, but it isn't even covered in the API docs… — coreyward, Apr 16 '11 at 02:11
read http://guides.rubyonrails.org/routing.html, you can do the toggle very easily using jQuery and unless your uncomfortable with replying on javascript is probably one of the better solutions, another option is to use nested routes and pass a param to a before filter in both models controller. — jvatic, Apr 16 '11 at 02:18
@jvaltic You aren't understanding the problem at all. I need to determine the route segments (e.g. "/yadda/yadda/:segment/yadda") for the current request. To do that I need to 1.) get the actual route object that maps to the current URL and 2.) call `route.segment_keys` to get the segments from it. — coreyward, Apr 16 '11 at 03:43

score 0 · Answer 1 · answered Oct 08 '12 at 19:31

Do you need all the segment keys or just a certain kind?

I was able to get just the literal keys with this code

Rails.application.routes.routes.collect do |i|
  i.path.spec.grep(Journey::Nodes::Literal).collect(&:left)
end

That got me just just the array of literal segments - I bet you could modify that to count the number of segment keys that exist (or do it once for literals and once for the symbols) Journey::Nodes::Cat supports to_s which will give you the original string used to construct the route and to_regexp which will give you a regex you can run against request.path

score 0 · Answer 2 · answered Apr 06 '15 at 15:37

Would something like this help? It resolves a path to a route hash.

> uri = URI("http://localhost:3000/items/2015/3") # some URI for your request, or the URL/Path in question
> Rails.application.routes.recognize_path(uri.path)
=> {:controller=>"items", :action=>"index", :year=>"2015", :month=>"03"}

score 0 · Answer 3 · answered Dec 14 '11 at 22:39

I had a case where I need to do something like this, so I added a method in my application_helper.rb:

def display_sub_navigation
  if admin_signed_in?
    url_path = request.fullpath.split("/")
    if url_path.size > 3 && File.exists?( Rails.root.join("app/views/shared/_#{url_path[2]}_sub_navigation.html.erb") )
      render :partial => "/shared/#{url_path[2]}_sub_navigation"
    end
  end
end

As you can see using the request.fullpath.split("/") creates an array I assign to url_path. From here, I can extract out what I want or count the number of elements in the array. I hope this pushes you in the right direction.

How to get segment keys from a Rails 3 route?

3 Answers3