Rails routes redirect for query string

Building on Alejandra's answer, more verbose but without the ? if there's no query string:

get "/old/report/:client", to: redirect{ |params, request| ["/new/report/#{params[:client]}", request.query_string.presence].compact.join('?') }

So /old/report/:client?with=param will become /new/report/:client?with=param, and /old/report/:client will become /new/report/:client.

The question mention by Matt helped me to figure out my answer (thanks a lot!). It was a slightly different for my specific case. Im leaving the answer that worked for me for future reference.

match "/old/report/:client" => redirect{ |params, request| "/new/report/#{params[:client]}?#{request.query_string}" }

Modify redirect to use the path: option to preserve the querystring:

- get '/old/about', to: redirect('/new/about')
+ get '/old/about', to: redirect(path: '/new/about')

This is demonstrated in the API docs for redirect, see http://api.rubyonrails.org/classes/ActionDispatch/Routing/Redirection.html#method-i-redirect