Two possible ways to implement a basic in-memory cache for DB queries. One is more idiomatic, but I wonder if it's too idiomatic.

query_cache_example.rb

class UserImporter < ImporterBase
  def import_user
    user_name = @data[:user_name]

    # Which is easier to understand?
    users_by_name[user_name]
    # -- OR --
    find_user_by_name(user_name)
  end

  def users_by_name
    @users_by_name ||= Hash.new do |hash, key|
      users = User.where(name: name).all
      hash[name] = users.first
    end
  end

  def find_user_by_name(name)
    @users_by_name ||= {}

    if @users_by_name.key?(name)
      @users_by_name[name]
    else
      users = User.where(name: name).all
      hash[name] = users.first

      @users_by_name[name] = users.first
    end
  end
end