Exclude all other resources from subdomain in Rails - ruby-on-rails

Question

I have a Rails 4.0 app with that allows users to access blogs through subdomains. My routes currently look like this:
match '', to: 'blogs#show', via: [:get, :post], constraints: lambda { |r| r.subdomain.present? && r.subdomain != 'www' }
resources :foobars
Now, when I navigate to somesubdomain.example.com I am indeed taken to the showaction of the blogs controller action, as expected.
When I navigate to example.com/foobars I can access the index action of the foobars controller, as expected.
However, I only get a behavior I do not desire:
When I navigate to somesubdomain.example.com/foobars, I can still access the the index action of foobars controller.
Is there a way to limit or exclude all resources that I do not specifically allow for a particular subdomain (i.e. somesubdomain.example.com/foobars will not work unless otherwise specified).
Thanks!

Answer 1

If you need to define a specific subdomain to exclude from a set of routes you can simply do this (uses negative lookahead regex):
# exclude all subdomains with 'www'
constrain :subdomain => /^(?!www)(\w+)/ do
root to: 'session#new'
resources :foobars
end
Or similarly, to define a specific subdomain to include a set of routes you could do this:
# only for subdomain matching 'somesubdomain'
constrain :subdomain => /^somesubdomain/ do
root to: 'blog#show'
resources :foobars
end
Another approach would be to define the constraint match in a class (or module) and then wrap all routes within constraints block:
class WorldWideWebSubdomainConstraint
def self.matches?(request)
request.subdomain.present? && request.subdomain != 'www'
end
end
App::Application.routes.draw do
# All "www" requests handled here
constraints(WorldWideWebSubdomainConstraint.new) do
root to: 'session#new'
resources :foobars
end
# All non "www" requests handled here
root to: 'blogs#show', via: [:get, :post]
end