Using a wildcard syntax (*) when defining routes in routes.rb, we can slurp up URL segments and make them available in our controller params. Here’s an example:

Globbing Example

# config/routes.rb

get 'photos/*path', to: 'photos_controller#index'

Now in the PhotosController you can access the globbed segments in the params hash. Let’s say the request comes in on photos/familiy/cousins.

def index
  path = params[:path] # 'family/counsins'

Catch-all Route

I can’t think of many reasons why we’d want to use route globbing. If you know some good used cases, please comment below. A catch-all route is one possible use case.

Rails will use the first defined route starting from the top of routes.rb that matches a request URL. So, if a wildcard, globbed route is defined last, this will be used as a catch-all route for a request that doesn’t match any of the previously defined routes.

# config/routes.rb at the bottom

match '*path', to: 'static_pages_controller#not_found', via: :all

Any request that comes in on a URL that doesn’t match any other previously defined route, will be routed to the StaticPagesController’s not_found action. The via: :all ensures that it will match against any HTTP verb. Alternatively, we can be explicit about which HTTP verbs we want to match by using any array of verbs: via: [:get, :edit].

Or if you’re too lazy to make a controller and view, you can give it a proc or lambda.

# config/routes.rb at the bottom

match '*path', to: ->(env) { [404, {}, ['Not Found']] }, via: :all

Side Note This works because routes are losely coupled to controllers. Hence, a request can be handled any object that responds to .call and takes a single argument.