patch to add sequel support to a new rails3 app

gistfile1.diff

diff --git a/app/models/model.rb b/app/models/model.rb
new file mode 100644
index 0000000..14c4620
--- /dev/null
+++ b/app/models/model.rb
@@ -0,0 +1,2 @@
+class Model < Sequel::Model
+end
\ No newline at end of file
diff --git a/config/application.rb b/config/application.rb
index 43d772f..6bc5bf0 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -1,6 +1,11 @@
 require File.expand_path('../boot', __FILE__)
 
-require 'rails/all'
+# Since we don't need ActiveRecord or ActiveResource we'll just pick
+# which frameworks to include in our app
+# require 'rails/all'
+require 'active_support/all'
+require 'action_controller/railtie'
+require 'action_mailer/railtie'
 
 # If you have a Gemfile, require the gems listed there, including any gems
 # you've limited to :test, :development, or :production.
diff --git a/config/initializers/sequel.rb b/config/initializers/sequel.rb
new file mode 100644
index 0000000..231a6f9
--- /dev/null
+++ b/config/initializers/sequel.rb
@@ -0,0 +1,45 @@
+# TODO modify sequel serialization plugin to use yajl as a backend
+require 'yajl/json_gem'
+JSON.default_options.merge! :symbolize_keys=>true
+
+module Kernel
+  if defined? id
+    undef :id
+    undef :type
+  end
+end
+
+module Sequel
+  class Dataset
+    def size
+      count
+    end
+  end
+end
+
+# Setup plugins and extensions we're using
+Sequel.extension :pagination
+Sequel.extension :pretty_table
+
+Sequel::Model.unrestrict_primary_key
+Sequel::Model.plugin :hook_class_methods
+Sequel::Model.plugin :active_model
+Sequel::Model.plugin :validation_helpers
+Sequel::Model.plugin :timestamps
+Sequel::Plugins::ValidationHelpers::DEFAULT_OPTIONS[:presence].update(
+  :message => lambda{"is missing"}
+)
+
+# this lives in /lib
+require File.expand_path('../../../lib/sequel_extensions', __FILE__)
+
+Sequel.default_timezone = :utc
+
+# clear out any existing connections
+Sequel::DATABASES.clear
+Sequel::Model.db = nil
+
+# connect to the db configured for the current Rails.env
+DB = Sequel.connect(Rails.configuration.database_configuration[Rails.env])
+
+DB.loggers << Rails.logger
\ No newline at end of file
diff --git a/db/migrate/20100623000000_model.rb b/db/migrate/20100623000000_model.rb
new file mode 100644
index 0000000..1dca971
--- /dev/null
+++ b/db/migrate/20100623000000_model.rb
@@ -0,0 +1,22 @@
+Class.new(Sequel::Migration) do
+  def up
+    create_table :models do
+      primary_key :id
+      varchar     :name, :null => false
+      int         :size
+      blob        :data
+      datetime    :created_at
+
+      index       :created_at
+    end
+    alter_table :models do
+      drop_column :name
+      add_column  :description, :blob
+      set_column_type :description, :text
+    end
+  end
+
+  def down
+    drop_table :models
+  end
+end
\ No newline at end of file
diff --git a/lib/sequel_extensions.rb b/lib/sequel_extensions.rb
new file mode 100644
index 0000000..4a47b63
--- /dev/null
+++ b/lib/sequel_extensions.rb
@@ -0,0 +1,49 @@
+require 'securerandom'
+
+class Sequel::Model
+  def type
+    self[:type]
+  end
+
+  def_dataset_method :on_duplicate_key_update, :insert_ignore
+
+  def set_columns(params, *fields)
+    fields = fields.flatten
+    params = params.reject{ |k,v| !fields.include?(k.to_sym) }
+    set_only(params, fields)
+  end
+
+  def save!
+    save(:validate=>false)
+  end
+
+  def full_messages(options = {})
+    full_messages = []
+
+    @errors.each_key do |attr|
+      @errors[attr].each do |message|
+        next unless message
+
+        if attr == "base"
+          full_messages << message
+        else
+          attr_name = @base.class.human_attribute_name(attr)
+          full_messages << attr_name + I18n.t('activerecord.errors.format.separator', :default => ' ') + message
+        end
+      end
+    end
+    full_messages
+  end
+
+  alias :attributes :values
+end
+
+class Sequel::Dataset
+  def keyed_hash(key)
+    inject({}){|h,v| h.update v[key] => v }
+  end
+
+  def keyed_arr_hash(key)
+    inject(Hash.new{|ho,k| ho[k] = []}){|h,v| h[v[key]] << v; h}
+  end
+end
\ No newline at end of file
diff --git a/lib/sequel_migration.rb b/lib/sequel_migration.rb
new file mode 100644
index 0000000..233b9eb
--- /dev/null
+++ b/lib/sequel_migration.rb
@@ -0,0 +1,159 @@
+require File.expand_path('../config/application', __FILE__)
+require 'active_record/errors'
+require 'active_record/migration'
+
+DB = Sequel.connect(Rails.configuration.database_configuration[Rails.env])
+DB.loggers << Logger.new(STDOUT)
+
+if defined? ActiveRecord::Base
+  raise "cannot use the migration hack if ActiveRecord::Base exists"
+else
+  module ActiveRecord::Base
+    class << self
+      def connection
+        unless DB.respond_to?(:initialize_schema_migrations_table)
+          def DB.initialize_schema_migrations_table
+            unless table_exists?(:schema_migrations)
+              create_table(:schema_migrations) do
+                varchar :version, :null => false, :unique => true
+              end
+
+              if table_exists?(:schema_info)
+                version = DB[:schema_info].get(:version)
+                migrated = DB[:schema_migrations].select(:version).map(:version).map(&:to_i)
+
+                migrations_path = ActiveRecord::Migrator.migrations_path
+                versions = Dir["#{migrations_path}/[0-9]*_*.rb"].map do |filename|
+                  filename.split('/').last.split('_').first.to_i
+                end
+
+                DB[:schema_migrations].insert_ignore.insert(:version => version)
+
+                inserted = Set.new
+                (versions - migrated).each do |v|
+                  if inserted.include?(v)
+                    raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict."
+                  elsif v < version
+                    DB[:schema_migrations].insert(:version => v)
+                    inserted << v
+                  end
+                end
+
+                DB.drop_table(:schema_info)
+              end
+            end
+          end
+          def DB.supports_migrations?
+            true
+          end
+          def DB.supports_ddl_transactions?
+            false
+          end
+        end
+
+        DB
+      end
+      def logger
+        DB.loggers.first
+      end
+      def transaction(&blk)
+        DB.transaction(&blk)
+      end
+    end
+  end
+end
+
+module Sequel
+  extension :migration
+  remove_const :Migrator
+  class Migration
+    class << self
+      def migrate(direction)
+        case direction
+          when :up   then announce "migrating"
+          when :down then announce "reverting"
+        end
+
+        result = nil
+        time = Benchmark.measure { result = new(DB).send(direction) }
+
+        case direction
+          when :up   then announce "migrated (%.4fs)" % time.real; write
+          when :down then announce "reverted (%.4fs)" % time.real; write
+        end
+
+        result
+      end
+
+      def write(text="")
+        puts(text)
+      end
+
+      def announce(message)
+        version = defined?(@version) ? @version : nil
+
+        text = "#{version} #{name}: #{message}"
+        length = [0, 75 - text.length].max
+        write "== %s %s" % [text, "=" * length]
+      end
+    end
+  end
+  class MigrationProxy < ActiveRecord::MigrationProxy
+    def load_migration
+      Migration.descendants.clear
+      load(File.expand_path(filename))
+      klass = Migration.descendants.last
+      klass
+    end
+  end
+  class Migrator < ActiveRecord::Migrator
+    class << self
+      def schema_migrations_table_name
+        :schema_migrations
+      end
+      def migrations_table
+        DB[schema_migrations_table_name]
+      end
+      def get_all_versions
+        migrations_table.select(:version).map(:version).map(&:to_i).sort
+      end
+      def current_version
+        if DB.table_exists?(schema_migrations_table_name)
+          migrations_table.order(:version.desc).limit(1).get(:version) || 0
+        else
+          0
+        end
+      end
+      def proper_table_name(name)
+        name
+      end
+    end
+
+    def migrations
+      unless @migrations
+        super
+        @migrations.map!{ |m|
+          o = MigrationProxy.new
+          o.name, o.version, o.filename = m.name, m.version, m.filename
+          o
+        }
+      end
+      @migrations
+    end
+
+    def record_version_state_after_migrating(version)
+      @migrated_versions ||= []
+      if down?
+        @migrated_versions.delete(version)
+        self.class.migrations_table.where(:version => version).delete
+      else
+        @migrated_versions.push(version).sort!
+        self.class.migrations_table.insert(:version => version)
+      end
+    end
+
+    def ddl_transaction
+      yield # assume no transactions for ddl (mysql)
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/tasks/sequel.rake b/lib/tasks/sequel.rake
new file mode 100644
index 0000000..2f20b78
--- /dev/null
+++ b/lib/tasks/sequel.rake
@@ -0,0 +1,147 @@
+# TODO: DRY these up
+namespace :db do
+  namespace :schema do
+    desc "Create a db/schema.rb file that can be portably used against any DB supported by Sequel"
+    task :dump do
+      Sequel.extension :schema_dumper
+      db = Sequel.connect(Rails.configuration.database_configuration[Rails.env])
+      File.open(ENV['SCHEMA'] || "#{Rails.root}/db/schema.rb", "w") do |file|
+        file.write(db.dump_schema_migration)
+      end
+      Rake::Task["db:schema:dump"].reenable
+    end
+    
+    desc "Load a schema.rb file into the database"
+    task :load do
+      file = ENV['SCHEMA'] || "#{Rails.root}/db/schema.rb"
+      if File.exists?(file)
+        load(file)
+      else
+        abort %{#{file} doesn't exist yet. Run "rake db:migrate" to create it then try again. If you do not intend to use a database, you should instead alter #{Rails.root}/config/boot.rb to limit the frameworks that will be loaded}
+      end
+    end
+  end
+
+  namespace :create do
+    desc 'Create all the local databases defined in config/database.yml'
+    task :all do
+      Rails.configuration.database_configuration.each_value do |config|
+        next unless config['database']
+        database = config.delete('database')
+        DB = Sequel.connect(config)
+        default_options = "DEFAULT CHARSET utf8 COLLATE utf8_unicode_ci"
+        puts "Creating database \"#{config['database']}\" if it doesn't already exist"
+        DB.run "CREATE DATABASE IF NOT EXISTS `#{config['database']}` /*!40100 #{default_options} */"
+      end
+    end
+  end
+
+  desc "Create the database defined in config/database.yml for the current Rails.env - also creates the test database if Rails.env.development?"
+  task :create do
+    connect_options = Rails.configuration.database_configuration[Rails.env]
+    connect_options.delete('database')
+    DB = Sequel.connect(connect_options)
+    default_options = "DEFAULT CHARSET utf8 COLLATE utf8_unicode_ci"
+    puts "Creating database \"#{Rails.configuration.database_configuration[Rails.env]['database']}\" if it doesn't already exist"
+    DB.run "CREATE DATABASE IF NOT EXISTS `#{Rails.configuration.database_configuration[Rails.env]['database']}` /*!40100 #{default_options} */"
+    if Rails.env.development? && Rails.configuration.database_configuration['test']
+      puts "Creating database \"#{Rails.configuration.database_configuration['test']['database']}\" if it doesn't already exist"
+      DB.run "CREATE DATABASE IF NOT EXISTS `#{Rails.configuration.database_configuration['test']['database']}` /*!40100 #{default_options} */"
+    end
+  end
+  
+  namespace :drop do
+    desc 'Drops all the local databases defined in config/database.yml'
+    task :all do
+      Rails.configuration.database_configuration.each_value do |config|
+        next unless config['database']
+        database = config.delete('database')
+        DB = Sequel.connect(config)
+        puts "Dropping database #{database} if it exists"
+        DB.run "DROP DATABASE IF EXISTS `#{database}`"
+      end
+    end
+  end
+  
+  desc "Create the database defined in config/database.yml for the current Rails.env - also creates the test database if Rails.env.development?"
+  task :drop do
+    connect_options = Rails.configuration.database_configuration[Rails.env]
+    connect_options.delete('database')
+    DB = Sequel.connect(connect_options)
+
+    puts "Dropping database #{Rails.configuration.database_configuration[Rails.env]['database']} if it exists"
+    DB.run "DROP DATABASE IF EXISTS `#{Rails.configuration.database_configuration[Rails.env]['database']}`"
+  end
+
+  namespace :migrate do
+    task :load do
+      require File.expand_path('../../sequel_migration', __FILE__)
+    end
+
+    desc  'Rollbacks the database one migration and re migrate up. If you want to rollback more than one step, define STEP=x. Target specific version with VERSION=x.'
+    task :redo => :load do
+      if ENV["VERSION"]
+        Rake::Task["db:migrate:down"].invoke
+        Rake::Task["db:migrate:up"].invoke
+      else
+        Rake::Task["db:rollback"].invoke
+        Rake::Task["db:migrate"].invoke
+      end
+    end
+
+    desc 'Resets your database using your migrations for the current environment'
+    task :reset => ["db:drop", "db:create", "db:migrate"]
+
+    desc 'Runs the "up" for a given migration VERSION.'
+    task :up => :load do
+      version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
+      raise "VERSION is required" unless version
+      Sequel::Migrator.run(:up, "db/migrate/", version)
+      Rake::Task["db:schema:dump"].invoke
+    end
+
+    desc 'Runs the "down" for a given migration VERSION.'
+    task :down => :load do
+      version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
+      raise "VERSION is required" unless version
+      Sequel::Migrator.run(:down, "db/migrate/", version)
+      Rake::Task["db:schema:dump"].invoke
+    end
+  end
+  
+  desc 'Migrate the database to the latest version'
+  task :migrate => :'migrate:load' do
+    Sequel::Migrator.migrate("db/migrate/", ENV["VERSION"] ? ENV["VERSION"].to_i : nil)
+    Rake::Task["db:schema:dump"].invoke
+  end
+
+  desc 'Rolls the schema back to the previous version. Specify the number of steps with STEP=n'
+  task :rollback => :'migrate:load' do
+    step = ENV['STEP'] ? ENV['STEP'].to_i : 1
+    Sequel::Migrator.rollback('db/migrate/', step)
+    Rake::Task["db:schema:dump"].invoke
+  end
+
+  desc 'Pushes the schema to the next version. Specify the number of steps with STEP=n'
+  task :forward => :'migrate:load' do
+    step = ENV['STEP'] ? ENV['STEP'].to_i : 1
+    Sequel::Migrator.forward('db/migrate/', step)
+    Rake::Task["db:schema:dump"].invoke
+  end
+  
+  desc 'Load the seed data from db/seeds.rb'
+  task :seed => :environment do
+    seed_file = File.join(Rails.root, 'db', 'seeds.rb')
+    load(seed_file) if File.exist?(seed_file)
+  end
+  
+  desc 'Create the database, load the schema, and initialize with the seed data'
+  task :setup => [ 'db:create', 'db:migrate', 'db:seed' ]
+  
+  desc 'Drops and recreates the database from db/schema.rb for the current environment and loads the seeds.'
+  task :reset => [ 'db:drop', 'db:setup' ]
+  
+  namespace :test do
+    task :prepare => ['db:reset']
+  end
+end