Rails Routes - slash character vs hash character

Question

In urls and rails routing, what is the difference between using a slash character vs a pound sign (hash sign) character?

These work

get "/static_pages/about"
get 'about', to: 'static_pages#about', as: :about

These don't

get "/static_pages#about"
get 'about', to: 'static_pages/about', as: :about
get 'about', to: '/static_pages#about', as: :about

What code controls this behavior, and what is the deeper reason behind it?

ANSWER:

(The two people answered it very well, and I had trouble choosing which one to mark as the accepted answer. I wish to state my understanding of the answer in a different way that might help people.)

Once you use the / symbol, the string gets recognized as a url string appended to the base url. So a '#' character will be interpreted as part of the url, and urls don't like to take '#' characters.

In the case of not using a / character, the first word is recognized somehow as a controller name, which you follow up with a '#' and an action name.

Answer 1

The # in to: 'static_pages#about' means about action of static_pages_controller. The syntax is controller#action.

When you define get "/static_pages#about", static_pages#about becomes the controller for the route i.e. the # is only a character literal and #about does not mean about action. You should get a missing :controller error if static_pages#about controller does not exist.

The following route definition gives you /about path which maps to static_pages/about controller's about action, where static_pages could either be a namespace or a scope.

get 'about', to: 'static_pages/about', as: :about

The following route is invalid and should throw an error due to the leading slash / in to option.

get 'about', to: '/static_pages#about', as: :about

Answer 2

In ruby, the hash symbol generally precedes the name of a instance method of a class. See the left sidebar of the page of the Array class documentation (http://www.ruby-doc.org/core-2.1.0/Array.html).

get "/static_pages#about" doesn't work because #about is not part of the url.

get 'about', to: 'static_pages/about', as: :about doesn't work because /about doesn't indicate which controller method should be called.

get 'about', to: '/static_pages#about', as: :about doesn't work because of the preceding slash before static_pages.