Rails: Request-based (& Database-based) Routing - ruby-on-rails

Question

I am trying to get rid of some scope-prefixes I am currently using in my app.
At the moment my Routes look like this (simplified example):
scope 'p'
get ':product_slug', as: :product
end
scope 't' do
get ':text_slug', as: :text
end
which for example generates these paths:
/p/car
/t/hello-world
Now I want the paths to work without the prefixed letters (p & t). So I restrict the slugs to the existing database entries (which btw works great):
text_slugs = Text.all.map(&:slug)
get ':text_slug', as: :text, text_slug: Regexp.new( "(#{text_slugs.join('|')})"
product_slugs = Product.all.map(&:slug)
get ':product_slug', as: :product, product_slug: Regexp.new( "(#{product_slugs.join('|')})"
The problem:
This is a multi-tenant app which means that someones text_slug could be another ones product_slug and vice versa. That's why I have to filter the slugs by the current site (by domain).
A solution would look like this:
text_slugs = Site.find_by_domain(request.host).texts.all.map(&:slug)
get ':text_slug', as: :text, text_slug: Regexp.new( "(#{text_slugs.join('|')})"
But request isn't available in routes.rb and I everything I tried won't work.
The direct call to Rack::Request needs the correct env variable which doesn't seem to be present in Application.routes, otherwise this could work:
req = Rack::Request.new(env)
req.host
I really tried alot and am thankful for any hint!

Answer 1

You may be able to use advanced constraints for this: http://guides.rubyonrails.org/routing.html#advanced-constraints.
class SlugConstraint
def initialize(type)
#type = type
end
def matches?(request)
# Find users subdomain and look for matching text_slugs - return true or false
end
end
App::Application.routes.draw do
match :product_slug => "products#index", :constraints => SlugConstraint.new(:product)
match :tag_slug => "tags#index", :constraints => SlugConstraint.new(:tag)
end
BTW - You may run into problems with testing, but that's another issue...