A Postgres ActiveRecord::SessionStore::SqlBypass library for Rails

postgres_session_store.rb

class PostgresSessionStore < ActiveRecord::SessionStore::SqlBypass
  @@session_id_column = 'id'
  @@schema_name = 'system'
  cattr_accessor :schema_name

  class << self
    def marshal(data)
      ::Base64.encode64(Marshal.dump(data)).chomp if data
    end

    def unmarshal(data)
      Marshal.load(::Base64.decode64(data)) if data
    end

    def create_table!
      connection.execute <<-SQL

do $$
begin
  perform schema_name from information_schema.schemata where schema_name = '#{schema_name}';
  if not found then
    create schema #{schema_name};
  end if;
end;
$$ language 'plpgsql';

create unlogged table #{connection.quote_table_name(schema_name)}.#{connection.quote_table_name(table_name)} (
  #{session_id_column} varchar primary key,
  data text,
  created_at timestamp,
  updated_at timestamp
);
      SQL
    end

    def drop_table!
      connection.execute <<-SQL

drop table #{schema_name}.#{table_name};
      SQL
    end

    def find_by_session_id(session_id)
      if record = connection.select_one("select * from #{connection.quote_table_name(schema_name)}.#{connection.quote_table_name(table_name)} where #{connection.quote_column_name(session_id_column)} = #{connection.quote(session_id)} limit 1")
        new(:session_id => session_id, :marshaled_data => record['data'])
      end
    end
  end

  def initialize(attributes)
    @current_marshaled_data = attributes[:marshaled_data]
    super
  end

  def save
    return false unless loaded?

    marshaled_data = self.class.marshal(data)

    return if @current_marshaled_data == marshaled_data

    if @new_record
      @new_record = false
      connection.update <<-SQL, 'Create session'

insert into #{connection.quote_table_name(schema_name)}.#{connection.quote_table_name(table_name)} (#{connection.quote_column_name(session_id_column)}, #{connection.quote_column_name(data_column)}, "created_at", "updated_at")
values (#{connection.quote(session_id)}, #{connection.quote(marshaled_data)}, now(), now())
      SQL
    else
      connection.update <<-SQL, 'Update session'

update #{connection.quote_table_name(schema_name)}.#{connection.quote_table_name(table_name)}
set #{connection.quote_column_name(data_column)} = #{connection.quote(marshaled_data)}, "updated_at" = now()
where #{connection.quote_column_name(session_id_column)} = #{connection.quote(session_id)}
      SQL
    end
  end

  def destroy
    return if @new_record

    connect = connection
    connect.delete <<-SQL, 'Destroy session'

delete from #{connection.quote_table_name(schema_name)}.#{connection.quote_table_name(table_name)} where #{connect.quote_column_name(session_id_column)} = #{connect.quote(session_id)}
    SQL
  end
end