Like find(:first), but asserts that query returns exactly one element. Works with scopes.

gistfile1.txt

class MyModel < ActiveRecord::Base
  def self.one(find_hash={})
    results = find(:all, find_hash)
    if results.size != 1
      raise "Expected one record, found #{results.size}"
    else
      return results[0]
    end
  end
end