Codes that demonstrates ArticleRepository.adapter is nil

gistfile1.rb

require 'bundler/setup'
require 'sqlite3'
require 'lotus/model'
require 'lotus/model/adapters/sql_adapter'

connection_uri = "sqlite://#{ __dir__ }/test.db"

database = Sequel.connect(connection_uri)

database.create_table! :authors do
  primary_key :id
  String  :name
end

database.create_table! :articles do
  primary_key :id
  Integer :author_id,      null: false
  String  :title
  Integer :comments_count, default: 0
  Boolean :published,      default: false
end

Author = Struct.new(:id, :name) do
  def initialize(attributes = {})
    @id, @name = attributes.values_at(:id, :name)
  end
end

class Article
  include Lotus::Entity
  self.attributes = :author_id, :title, :comments_count, :published # id is implicit

  def published?
    !!published
  end

  def publish!
    @published = true
  end
end

class AuthorRepository
  include Lotus::Repository
end

class ArticleRepository
  include Lotus::Repository

  def self.most_recent_by_author(author, limit = 8)
    query do
      where(author_id: author.id).
        desc(:id).
        limit(limit)
    end
  end

  def self.most_recent_published_by_author(author, limit = 8)
    most_recent_by_author(author, limit).published
  end

  def self.published
    query do
      where(published: true)
    end
  end

  def self.drafts
    exclude published
  end

  def self.rank
    published.desc(:comments_count)
  end

  def self.best_article_ever
    rank.limit(1).first
  end

  def self.comments_average
    query.average(:comments_count)
  end
end

mapper = Lotus::Model::Mapper.new do
  collection :authors do
    entity Author

    attribute :id,   Integer
    attribute :name, String
  end

  collection :articles do
    entity Article

    attribute :id,             Integer
    attribute :author_id,      Integer
    attribute :title,          String
    attribute :comments_count, Integer
    attribute :published,      Boolean
  end
end

adapter = Lotus::Model::Adapters::SqlAdapter.new(mapper, connection_uri)
AuthorRepository.adapter  = adapter
ArticleRepository.adapter = adapter

mapper.load!

author = Author.new(name: 'Luca')
AuthorRepository.create(author)