rails_4_find_by.rb

# Add this to your Rails 3.2 project to add in approximations of the Rails 4
# finders and disable Rails 2/3 'dynamic' finders.

module ActiveRecord
  # Approximations of the new Rails 4 finders
  class Relation
    def take
      first
    end

    def take!
      first!
    end

    def find_by(*args)
      where(*args).take
    end

    def find_by!(*args)
      where(*args).take!
    end

    def find_or_initialize_by(attributes, &block)
      find_by(attributes) || new(attributes, &block)
    end

    def find_or_create_by(attributes, &block)
      find_by(attributes) || create(attributes, &block)
    end

    def find_or_create_by!(attributes, &block)
      find_by(attributes) || create!(attributes, &block)
    end
  end

  # Relation methods also need to work on our root scope
  class Base
    class << self
      %w{find_by find_by! find_or_initialize_by find_or_create_by find_or_create_by!}.each do |m|
        define_method m do |*args, &block|
          scoped.send(m, *args, &block)
        end
      end
    end
  end

  # Force dynamic finders to never work by overriding the magic used to match them.
  class DynamicFinderMatch
    def self.match(method)
      case method.to_s
      when /^find_(all_|last_)?by_([_a-zA-Z]\w*)$/, /^find_by_([_a-zA-Z]\w*)\!$/, /^find_or_create_by_([_a-zA-Z]\w*)\!$/, /^find_or_(initialize|create)_by_([_a-zA-Z]\w*)$/
        ActiveSupport::Deprecation.warn("Dynamic matcher #{method} called - please remove!", caller)
      end
      nil
    end
  end
end