Ruby routes URI regex

Question

I have blog web application on Roda where links have the following URL format: example.com/posts/<id>/<slug>.

For example example.com/posts/1/example-blog-post.

What I want to achieve is to redirect user to example.com/posts/1/example-blog-post in case he either visits:

1. example.com/posts/1 or
2. example.com/posts/1/ (note last backslash)

That's what I got in routes so far:

r.on /posts\/([0-9]+)\/(.*)/ do |id, slug|
  @post = Post[id]

  if URI::encode(@post[:slug]) == slug
    view("blogpage")
  else
    r.redirect "/posts/#{id}/#{@post[:slug]}"
  end
end

With this code:

1. example.com/posts/1 - FAILS
2. example.com/posts/1/ - OK

Can I satisfy both conditions?

Answer 1

You could wrap the forward slash followed by the second capturing group in an optional non capturing group:

posts\/([0-9]+)(?:\/(.*))?

Explanation

• posts\/ Match posts/
• ([0-9]+) Capture group 1, match 1+ digits
• (?: Non capture group
  • \/(.*) Match / and capture in group 2 0+ times any char except a newline
• )? Close non capture group and make it optional

Regex demo