The Highlander query with Rails’ ActiveRecord

For those cases in which there can be one and only one record on the database with certain fields and I don’t just want to get the first one and silently get the wrong one. I want to make sure there’s one and only one, so, I wrote this little extension to ActiveRecord that does exactly that:

module ActiveRecordExtension
  extend ActiveSupport::Concern

  class_methods do
    def one_and_only
      records = limit(2).all.to_a
      if records.count > 1
        raise "#{self} generated more than one record when expecting only one."

    def one_and_only!
      one_and_only.tap do |record|
        if record.nil?
          raise "#{self} didn't generate any records."

ActiveRecord::Base.send(:include, ActiveRecordExtension)

The first method, one_and_only, will raise an exception if there’s more than one item but it’ll return null if there aren’t any. one_and_only! will fail if there isn’t exactly one and only one record in the database.

If you don’t know why I’m calling this The Highlander query, you should go and watch Christopher Lambert’s masterpiece.


random_unique_id version 1.0.0 released

The core of random_unique_id was developed for Watu very early on, which means that it has been used in production for more than two years and a few thousands millions of records. It’s been released as a gem and we had a few iterations. It has 100% code coverage, code climate rating 4.0, 100% documentation coverage, a running continuous integration testing for many different versions of Ruby and Rails, up to date dependencies, it’s been downloaded more that 1700 times.

It’s time to release version 1.0.0. It’s ready for mass consumption. Get it while it’s hot!