got app working reasonably well, and removed db file, that shouldn't be in the db

app.rb

@@ -1,8 +1,12 @@
 require 'roda'
 require 'securerandom'
 require 'json'
+require 'sequel'
+require 'logger'
 
 class App < Roda
+  DB = Sequel.sqlite('db/url_shortener.db')
+  links = DB[:links]
   plugin :render, escape: true
   route do |r|
     r.root do
@@ -10,10 +14,15 @@ class App < Roda
     end
 
     r.get String do | url_code |
-      "redirect to url"
+      link = links.filter(:code => url_code).first[:url]
+      r.redirect link
     end
 
     r.post "create" do
+      url = r.params['url']
+      code = SecureRandom.urlsafe_base64 4
+      links.insert(url: url, code: code) 
+      @new_link = 'http://' + request.env['HTTP_HOST'] + '/' + links.filter(:url => url).first[:code]
       view :create   
     end
   end

views/create.erb

@@ -0,0 +1,2 @@
+<a href="/">Home</a>
+<h2><a href="<%= @new_link %>" target="_blank"><%= @new_link %></a></h2>