Port db:structure:load and db:structure:dump rake tasks from Rails 3.2 to Padrino

database_tasks.rb

module ActiveRecord
  module Tasks # :nodoc:
    module DatabaseTasks # :nodoc:
      extend self

      attr_writer :current_config

      LOCAL_HOSTS    = ['127.0.0.1', 'localhost']

      def register_task(pattern, task)
        @tasks ||= {}
        @tasks[pattern] = task
      end

      register_task(/postgresql/, ActiveRecord::Tasks::PostgreSQLDatabaseTasks)

      def current_config(options = {})
        options.reverse_merge! :env => Padrino.env
        if options.has_key?(:config)
          @current_config = options[:config]
        else
          @current_config ||= if ENV['DATABASE_URL']
                                database_url_config
                              else
                                ActiveRecord::Base.configurations[options[:env]]
                              end
        end
      end

      def create(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).create
      rescue Exception => error
        $stderr.puts error, *(error.backtrace)
        $stderr.puts "Couldn't create database for #{configuration.inspect}"
      end

      def create_all
        each_local_configuration { |configuration| create configuration }
      end

      def create_current(environment = Padrino.env)
        each_current_configuration(environment) { |configuration|
          create configuration
        }
        ActiveRecord::Base.establish_connection environment
      end

      def create_database_url
        create database_url_config
      end

      def drop(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).drop
      rescue Exception => error
        $stderr.puts error, *(error.backtrace)
        $stderr.puts "Couldn't drop #{configuration['database']}"
      end

      def drop_all
        each_local_configuration { |configuration| drop configuration }
      end

      def drop_current(environment = Padrino.env)
        each_current_configuration(environment) { |configuration|
          drop configuration
        }
      end

      def drop_database_url
        drop database_url_config
      end

      def charset_current(environment = Padrino.env)
        charset ActiveRecord::Base.configurations[environment]
      end

      def charset(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).charset
      end

      def collation_current(environment = Padrino.env)
        collation ActiveRecord::Base.configurations[environment]
      end

      def collation(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).collation
      end

      def purge(configuration)
        class_for_adapter(configuration['adapter']).new(configuration).purge
      end

      def structure_dump(*arguments)
        configuration = arguments.first
        filename = arguments.delete_at 1
        class_for_adapter(configuration['adapter']).new(*arguments).structure_dump(filename)
      end

      def structure_load(*arguments)
        configuration = arguments.first
        filename = arguments.delete_at 1
        class_for_adapter(configuration['adapter']).new(*arguments).structure_load(filename)
      end

      private

      def database_url_config
        @database_url_config ||=
               ConnectionAdapters::ConnectionSpecification::Resolver.new(ENV["DATABASE_URL"], {}).spec.config.stringify_keys
      end

      def class_for_adapter(adapter)
        key = @tasks.keys.detect { |pattern| adapter[pattern] }
        @tasks[key]
      end

      def each_current_configuration(environment)
        environments = [environment]
        environments << 'test' if environment.development?

        configurations = ActiveRecord::Base.configurations.values_at(*environments)
        configurations.compact.each do |configuration|
          yield configuration unless configuration['database'].blank?
        end
      end

      def each_local_configuration
        ActiveRecord::Base.configurations.each_value do |configuration|
          next unless configuration['database']

          if local_database?(configuration)
            yield configuration
          else
            $stderr.puts "This task only modifies local databases. #{configuration['database']} is on a remote host."
          end
        end
      end

      def local_database?(configuration)
        configuration['host'].blank? || LOCAL_HOSTS.include?(configuration['host'])
      end
    end
  end
end

db.rake

require 'active_record'

namespace :db do
  def filename
    @filename ||= ENV['DB_STRUCTURE'] || Padrino.root("db", "structure.sql")
  end

  def current_config
    @current_config ||= ActiveRecord::Tasks::DatabaseTasks.current_config.stringify_keys
  end

  task :compatibility do
    case current_config['adapter']
    when /postgresql/
      puts "Found a compatible #{current_config['adapter']} adapter."
    else
      raise "Task not supported by '#{current_config["adapter"]}'"
    end
  end

  namespace :structure do
    desc 'Dump the database structure to db/structure.sql. Specify another file with DB_STRUCTURE=db/my_structure.sql'
    task :dump => :compatibility do
      ActiveRecord::Tasks::DatabaseTasks.structure_dump(current_config, filename)

      if ActiveRecord::Base.connection.supports_migrations?
        File.open(filename, "a") { |f| f << ActiveRecord::Base.connection.dump_schema_information }
      end
    end

    # desc "Recreate the databases from the structure.sql file"
    task :load => :compatibility do
      ActiveRecord::Tasks::DatabaseTasks.purge(current_config)
      ActiveRecord::Tasks::DatabaseTasks.structure_load(current_config, filename)
    end
  end

end

postgresql_database_tasks.rb

require 'shellwords'

module ActiveRecord
  module Tasks # :nodoc:
    class PostgreSQLDatabaseTasks # :nodoc:

      DEFAULT_ENCODING = ENV['CHARSET'] || 'utf8'

      delegate :connection, :establish_connection, :clear_active_connections!,
        to: ActiveRecord::Base

      def initialize(configuration)
        @configuration = configuration
      end

      def create(master_established = false)
        establish_master_connection unless master_established
        connection.create_database configuration['database'],
          configuration.merge('encoding' => encoding)
        establish_connection configuration
      end

      def drop
        establish_master_connection
        connection.drop_database configuration['database']
      end

      def charset
        connection.encoding
      end

      def collation
        connection.collation
      end

      def purge
        clear_active_connections!
        drop
        create true
      end

      def structure_dump(filename)
        set_psql_env
        search_path = configuration['schema_search_path']
        unless search_path.blank?
          search_path = search_path.split(",").map{|search_path_part| "--schema=#{Shellwords.escape(search_path_part.strip)}" }.join(" ")
        end

        command = "pg_dump -i -s -x -O -f #{Shellwords.escape(filename)} #{search_path} #{Shellwords.escape(configuration['database'])}"
        raise 'Error dumping database' unless Kernel.system(command)

        File.open(filename, "a") { |f| f << "SET search_path TO #{ActiveRecord::Base.connection.schema_search_path};\n\n" }
      end

      def structure_load(filename)
        set_psql_env
        Kernel.system("psql -f #{filename} #{configuration['database']}")
      end

      private

      def configuration
        @configuration
      end

      def encoding
        configuration['encoding'] || DEFAULT_ENCODING
      end

      def establish_master_connection
        establish_connection configuration.merge(
          'database'           => 'postgres',
          'schema_search_path' => 'public'
        )
      end

      def set_psql_env
        ENV['PGHOST']     = configuration['host']          if configuration['host']
        ENV['PGPORT']     = configuration['port'].to_s     if configuration['port']
        ENV['PGPASSWORD'] = configuration['password'].to_s if configuration['password']
        ENV['PGUSER']     = configuration['username'].to_s if configuration['username']
      end
    end
  end
end