module ActionDispatch::Routing::Redirection

# File actionpack/lib/action_dispatch/routing/redirection.rb, line 177
def redirect(*args, &block)
  options = args.extract_options!
  status  = options.delete(:status) || 301
  path    = args.shift

  return OptionRedirect.new(status, options) if options.any?
  return PathRedirect.new(status, path) if String === path

  block = path if path.respond_to? :call
  raise ArgumentError, "redirection argument not supported" unless block
  Redirect.new status, block
end

Redirect any path to another path:

get "/stories" => redirect("/posts")

You can also use interpolation in the supplied redirect argument:

get 'docs/:article', to: redirect('/wiki/%{article}')

Note that if you return a path without a leading slash then the url is prefixed with the current SCRIPT_NAME environment variable. This is typically '/' but may be different in a mounted engine or where the application is deployed to a subdirectory of a website.

Alternatively you can use one of the other syntaxes:

The block version of redirect allows for the easy encapsulation of any logic associated with the redirect in question. Either the params and request are supplied as arguments, or just params, depending of how many arguments your block accepts. A string is required as a return value.

get 'jokes/:number', to: redirect { |params, request|
  path = (params[:number].to_i.even? ? "wheres-the-beef" : "i-love-lamp")
  "http://#{request.host_with_port}/#{path}"
}

Note that the +do end+ syntax for the redirect block wouldn't work, as Ruby would pass the block to get instead of redirect. Use { ... } instead.

The options version of redirect allows you to supply only the parts of the url which need to change, it also supports interpolation of the path similar to the first example.

get 'stores/:name',       to: redirect(subdomain: 'stores', path: '/%{name}')
get 'stores/:name(*all)', to: redirect(subdomain: 'stores', path: '/%{name}%{all}')

Finally, an object which responds to call can be supplied to redirect, allowing you to reuse common redirect routes. The call method must accept two arguments, params and request, and return a string.

get 'accounts/:name' => redirect(SubdomainRedirector.new('api'))