External link routes in rails - ruby-on-rails

Question

Simple enough. When were making a typical restful rails app we would keep all routes inside of our applicaiton. Very rarely would a path link to an external path. But if we were to do it, I'm wondering what the best way is.
A typical matching of home
match "home"=>"appcontroller#home"
If we were matching an external url to a variable of path. We might do something like the below?
First method
Routes.rb
match "external"=>"http:/www.google.ie"
Then in our html.erb
<%= link_to 'Google', external_path %>
Note this is not actually a legal way of doing things but something similar may exist. It seems very close to the current way of defining paths in rails but with an external landing.
Second method
Something that I've seen done elsewhere is to create a global variable for the external URL and use it in the link. EG.
in environment.rb or production.rb or whatever
#ext_path="http:/www.google.ie"
Then in our html.erb
<%= link_to 'Google', #ext_path %>
So to recap. Whats the best way to use external URLS in rails. Paths? Variables? Other?
Any input appreciated

Answer 1

I would have kept external links only in views. Because this links are not related to the any kind of logic of the application, and it's just an UI elements.
So, this way seems to me the best:
<%= link_to 'Google', "http://google.ie" %>
If you need to use this element many times, maybe it makes sense to bring this code into the helper, for example:
def search_engine_link
link_to 'Google', "http://google.ie"
end
And I really think that is's not very good place to introduce a more complex logic.

Answer 2

I'd probably use application-wide helpers wrapped around constants.
Helpers because I'd rather not see constants in templates, constants for environment-specific values.
I might use a hash to store the URLs: this keeps them more-tightly-coupled, and would allow environment-wide defaults, overriding per-environment as necessary.
The helpers could take symbols, or be generated from the hash keys, to generate xxx_path methods as happens with routes in routes.rb.

Answer 3

I found myself needing to do this because I had a link to an external site which I intended to make local in future.
In Rails 4 you can add this to config/routes.rb:
get '/contact',
to: redirect('http://www.example.com/contact.php'),
as: 'contact_us'
Which at the price of an extra redirect, lets you write:
<%= link_to "Contact us", contact_us_path %>

Answer 4

301-redirects
A note about use of redirect(...) in the routes file. Redirect generates a 301-redirect, which is a specific thing, Google describes it as...
If you need to change the URL of a page as it is shown in search
engine results, we recommend that you use a server-side 301 redirect.
This is the best way to ensure that users and search engines are
directed to the correct page. The 301 status code means that a page
has permanently moved to a new location.
So, using a 301-redirect in your routes for links to external websites may work, which it does, but the status information that is carried with that redirect is not correct.
If you've moved pages in your web app and want to tell the Google index (and everyone else) about it, then by all means use the redirect() to assure Google updates the index, but it's not optimal to use for standard external links out of your web app.