How to match a literal colon in a route

I’m trying to figure out how to escape a literal colon in the routes. If I make a route like this:

get ‘/thing:/:id’ => ‘things#show’

then ‘/thing:/123’ does not match on this route

I’ve also tried ‘/thing:/:id’ and ‘/thing%3A/:id’ none seem to work.

Does anyone have any tips here?


Yes - don't do that :slight_smile:

See, specifically Section 2.2 on
reserved characters.

I’d certainly prefer not to, but it is prescribed by the ARK standard:


I did some digging on this, and I couldn’t find a way to make this work with a literal in the route itself.

Splatting works, though:

get ‘baz/*ark_tag/:id/bar’ => ‘welcome#index’, constraints: { ark_tag: ‘ark:’ }, as: :ark

will only match paths like “/baz/ark:/123/bar”.

It’s a little fussy with URL helpers, as you need to always specify ark_tag or you’ll get an error:

ark_path(ark_tag: ‘ark:’, id: 1234)

You’ll probably want to define your own helpers that hide that.

The other, bigger issue is the OTHER features of the ARK spec that are going to confuse & annoy the default URL parser. In particular:

  • the dot-separated components of VariantPath elements. The default Rails behavior appends a .:format optional parameter to the route. This doesn’t allow further dots.

  • the ? and ?? suffixes. The single question-mark, in particular, is only detectable if you check the original request URI in the Rack request. I’m also unsure how to talk the regular path helpers into producing a single-question-mark URL.

If you’re building an application which relies on complex routing of ARK URLs, you may want to consider writing your own Rack middleware to hijack the URL parsing process and transmute them into something more palatable to the existing router.

–Matt Jones