A simple CLI tool that takes in an arbitrarily-long URL and will shorten it for the user. Subsequent users can then give the short URL back to the tool and be redirected to the original URL.

• Written in Ruby.
• Uses the launchy gem to allow us to pop open the URL in the browser without actually building in the browser.
• To see how it works:
  • make sure PostgreSQL is running.
  • run bundle install from within the project directory.
  • run ./setup.
    • if you get a permission error, run chmod +x setup and then ./setup again.
  • run rails runner bin/cli.
  • when prompted for an email: enter one of the emails already in the database, which you can find in db/seeds.rb.

• Tracks clickthroughs for business analytics.
• Allows users to choose from a set of predefined TagTopics for links (e.g., news, music, etc.).
  • Allows users to search for the most visited links by topic.
• Spam protection: users cannot submit more than 5 URLs in a single minute.
• A premium option is available for users: the number of total URLs non-premium users can submit is limited to 5.
• Stale URLs can be purged from the database with the ShortenedUrl::prune method or by running the Rake Task prune.rake in lib/tasks.

• building a CLI tool
• launchy gem
• Base64 encoding (SecureRandom)
• Associations
  • join table
  • dependent: :destroy
• ActiveRecord methods
  • exists?
  • ::create! vs ::new & #save! -> use create instead of new/save syntax in factory methods because the other class calling the factory method will get returned to it a "true" instead of the object
  • #attributes
• lazy evaluation of ActiveRecord::Relation objects
• ActiveRecord Query Interface
  • select
    • distinct chained onto select
  • where
    • find, find_by, find_by_#{attribute}, etc. all return the first matching instance from the DB, where returns a collection of instances, regardless of the number.
  • joins
  • group
  • limit
  • order
    • Rails 6 will need us to wrap our raw SQL in Arel.sql
• ActiveRecord time methods
  • Using the created_at column to interact with Time objects
• ActiveModel::EachValidator
  • custom url validation
• client-side email validation
• rails runner: loads the Rails environment for us, so we'll be able to use classes without requiring them explicitly. It also connects to the DB so we can query tables
• creating a Rake task