Mapping DM1 resources to veritas gateways

dm-veritas-gateway.rb

require 'dm-core'
require 'dm-migrations'

URI = 'postgres://localhost/test'.freeze

DataMapper::Logger.new($stdout, :debug)
DataMapper.setup(:default, URI)

class Account
  include DataMapper::Resource

  property :id,    Serial
  property :email, String, :required => true, :unique => true, :unique_index => true

  has 1, :person
end

class Person
  include DataMapper::Resource

  property :id,   Serial
  property :name, String, :required => true

  belongs_to :account, :unique => true
end

DataMapper.finalize.auto_migrate!

Account.create(:email => 'test@test.com', :person => Person.new(:name => 'snusnu'))

require 'pp'
require 'backports'
require 'backports/basic_object'
require 'veritas'
require 'veritas-do-adapter'
require 'veritas-optimizer'

module DataMapper
  module Veritas

    TYPE_MAP = {
      DataMapper::Property::Serial  => Integer,
      DataMapper::Property::String  => String,
      DataMapper::Property::Integer => Integer,
      # this is obviously incomplete ...
    }

    class Repository
      attr_reader :adapter
      attr_reader :registry

      def initialize(uri)
        @adapter  = ::Veritas::Adapter::DataObjects.new(uri)
        @registry = DataMapper::Veritas::RelationRegisty.new

        initialize_registry
      end

      def [](relation_name)
        @registry[relation_name]
      end

      private

      def initialize_registry
        DataMapper::Model.descendants.each do |model|
          name     = model.storage_names[:default]
          header   = model.properties.map { |property| [ property.name, DataMapper::Veritas::TYPE_MAP[property.class] ] }
          relation = ::Veritas::Relation::Base.new(name, header)

          registry << ::Veritas::Relation::Gateway.new(adapter, relation)
        end
      end
    end # class Repository

    class RelationRegisty

      def initialize(relations = {})
        @relations = relations
      end

      def [](name)
        @relations[name.to_sym]
      end

      def []=(name, relation)
        @relations[name.to_sym] = relation
      end

      def <<(relation)
        self[relation.name] = relation
      end
    end # class RelationRegisty
  end # module Veritas
end # DataMapper

class App
  def self.db
    @db ||= DataMapper::Veritas::Repository.new(URI)
  end
end

accounts = App.db[:accounts]
people   = App.db[:people]

accounts.each { |tuple| pp(tuple.to_ary) }

relation = accounts.join(people).optimize

relation.each { |tuple| pp(tuple.to_ary) }

__END__

 ~ (0.000368) SET backslash_quote = off
 ~ (0.000127) SET standard_conforming_strings = on
 ~ (0.000168) SET client_min_messages = warning
 ~ (0.000797) SELECT version()
 ~ (0.000120) SET client_min_messages = warning
 ~ (0.058407) DROP TABLE IF EXISTS "accounts"
 ~ (0.000231) RESET client_min_messages
 ~ (0.000145) SET client_min_messages = warning
 ~ (0.000427) SELECT current_schema()
 ~ (0.005512) SELECT COUNT(*) FROM "information_schema"."tables" WHERE "table_type" = 'BASE TABLE' AND "table_schema" = 'public' AND "table_name" = 'accounts'
 ~ (0.009155) CREATE TABLE "accounts" ("id" SERIAL NOT NULL, "email" VARCHAR(50) NOT NULL, PRIMARY KEY("id"))
 ~ (0.003243) CREATE UNIQUE INDEX "unique_accounts_email" ON "accounts" ("email")
 ~ (0.000248) RESET client_min_messages
 ~ (0.000227) SET client_min_messages = warning
 ~ (0.003470) DROP TABLE IF EXISTS "people"
 ~ (0.000150) RESET client_min_messages
 ~ (0.000130) SET client_min_messages = warning
 ~ (0.001146) SELECT COUNT(*) FROM "information_schema"."tables" WHERE "table_type" = 'BASE TABLE' AND "table_schema" = 'public' AND "table_name" = 'people'
 ~ (0.013248) CREATE TABLE "people" ("id" SERIAL NOT NULL, "name" VARCHAR(50) NOT NULL, "account_id" INTEGER NOT NULL, PRIMARY KEY("id"))
 ~ (0.002963) CREATE INDEX "index_people_account" ON "people" ("account_id")
 ~ (0.003103) CREATE UNIQUE INDEX "unique_people_account_id" ON "people" ("account_id")
 ~ (0.000227) RESET client_min_messages
 ~ (0.001573) INSERT INTO "accounts" ("email") VALUES ('test@test.com') RETURNING "id"
 ~ (0.001897) INSERT INTO "people" ("name", "account_id") VALUES ('snusnu', 1) RETURNING "id"
 ~ (0.000340) SET backslash_quote = off
 ~ (0.000138) SET standard_conforming_strings = on
 ~ (0.000514) SET client_min_messages = warning
 ~ (0.001514) SELECT "id", "email" FROM "accounts"
[1, "test@test.com"]
 ~ (0.001434) SELECT "id", "email", "name", "account_id" FROM "accounts" AS "left" NATURAL JOIN "people" AS "right"
[1, "test@test.com", "snusnu", 1]