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Rails 4。テーブルIDをUUIDに移行します

私はテーブルを持っています：db/migrate/20140731201801_create_voc_brands.rb：

class CreateVocBrands < ActiveRecord::Migration
  def change
    create_table :voc_brands do |t|
      t.string :name

      t.timestamps
    end
  end
end

しかし、テーブルをこれに変更する必要があります（ゼロから作成する場合）：

class CreateVocBrands < ActiveRecord::Migration
  def change
    create_table :voc_brands, :id => false do |t|
      t.uuid :id, :primary_key => true
      t.string :name

      t.timestamps
    end
    add_index :voc_brands, :id
  end
end

移行を使用してこれを変更するにはどうすればよいですか？

ruby-on-railsmigrationrails-migrations
19
Derk153

私はあなたと同じ問題を抱えていました。デフォルトのIDからuuidを使用するように移行するには、私が持っていたものと同様の何かができると思います。

class ChangeVocBrandsPrimaryKey < ActiveRecord::Migration
  def change
    add_column :voc_brands, :uuid, :uuid, default: "uuid_generate_v4()", null: false

    change_table :voc_brands do |t|
      t.remove :id
      t.rename :uuid, :id
    end
    execute "ALTER TABLE voc_brands ADD PRIMARY KEY (id);"
  end
end
30
willawill

移行はデータベースを変更するための好ましい方法ですが、以下のアプローチは素晴らしいです。 PostgreSQLへの直接クエリを使用して、既存のデータでテーブルを変換することができます。

主キーの場合：

    ALTER TABLE students
        ALTER COLUMN id DROP DEFAULT,
        ALTER COLUMN id SET DATA TYPE UUID USING (uuid(lpad(replace(text(id),'-',''), 32, '0'))),
        ALTER COLUMN id SET DEFAULT uuid_generate_v4()

その他の参考資料：

    ALTER TABLE students
        ALTER COLUMN city_id SET DATA TYPE UUID USING (uuid(lpad(replace(text(city_id),'-',''), 32, '0')))

左上は整数値にゼロを埋め込み、UUIDに変換します。このアプローチではIDマッピングは必要なく、必要に応じて古いIDを取得できます。

データのコピーがないため、このアプローチは非常に高速に機能します。

これらのより複雑な多態的な関連付けのケースを処理するには、 https://github.com/kreatio-sw/webdack-uuid_migration を使用してください。このgemは、ActiveRecord :: Migrationにヘルパーを追加して、これらの移行を容易にします。

3
Vaibhav

これが質問に直接答えないことは知っていますが、プロジェクトをidからuuidに変換するのに役立つrakeタスクを作成しました https://Gist.github.com/kuczmama/152d762177968f7192df1dea184e337

task id_to_uuid: :environment do
  puts "[START] Convert id to uuid"
  ActiveRecord::Base.connection.enable_extension 'uuid-ossp' unless ActiveRecord::Base.connection.extensions.include? 'uuid-ossp'
  ActiveRecord::Base.connection.enable_extension 'pgcrypto' unless ActiveRecord::Base.connection.extensions.include? 'pgcrypto'

  table_names = ActiveRecord::Base.connection.tables - ["schema_migrations", "ar_internal_metadata", "migration_validators"]
  table_names.each do |table_name|
    puts "[CREATE] uuid column for #{table_name}"

    #Make sure the column is a uuid if not delete it and then create it
    if ActiveRecord::Migration.column_exists? table_name, :uuid
      column_type = ActiveRecord::Migration.columns(table_name).select{|c| c.name == "uuid"}.try(:first).try(:sql_type_metadata).try(:type)
      if column_type && column_type != :uuid
        ActiveRecord::Migration.remove_column(table_name, :uuid)
      end
    end

    # Create it if it doesn't exist
    if !ActiveRecord::Migration.column_exists? table_name, :uuid
      ActiveRecord::Migration.add_column table_name, :uuid, :uuid, default: "uuid_generate_v4()", null: false
    end

  end

  # The strategy here has three steps.
  # For each association:
  # 1) write the association's uuid to a temporary foreign key _uuid column,
  # 2) For each association set the value of the _uuid column
  # 3) remove the _id column and
  # 4) rename the _uuid column to _id, effectively migrating our foreign keys to UUIDs while sticking with the _id convention.
  table_names.each do |table_name|
    puts "[UPDATE] change id to uuid #{table_name}"
    model = table_name.singularize.camelize.constantize
    id_columns = model.column_names.select{|c| c.end_with?("_id")}


    # write the association's uuid to a temporary foreign key _uuid column
    # eg. Message.room_id => Message.room_uuid
    model.reflections.each do|k, v|
      begin
        association_id_col = v.foreign_key
        # Error checking
        # Make sure the relationship actually currently exists
        next unless id_columns.include?(association_id_col)
        # Check that there is at

        # 1) Create temporary _uuid column set to nulll,
        tmp_uuid_column_name = column_name_to_uuid(association_id_col)
        unless ActiveRecord::Migration.column_exists?(table_name, tmp_uuid_column_name)
          puts "[CREATE] #{table_name}.#{tmp_uuid_column_name}"
          ActiveRecord::Migration.add_column(table_name, tmp_uuid_column_name, :uuid)
        end

        # 2) For each association set the value of the _uuid column
        #
        # For example.  Assume the following example
        #
        # message.room_id = 1
        # room = Room.find(1)
        # room.uuid = 0x123
        # message.room_uuid = 0x123
        #
        association_klass = v.klass

        model.unscoped.all.each do |inst|
          next unless inst.present?
          association = association_klass.find_by(id: inst.try(association_id_col.try(:to_sym)))
          next unless association.present?
          inst.update_column(tmp_uuid_column_name, association.try(:uuid))
        end

        # 3) Remove id column
        ActiveRecord::Migration.remove_column table_name, association_id_col if ActiveRecord::Migration.column_exists?(table_name, association_id_col)

        # 4) Rename uuid_col_name to id
        ActiveRecord::Migration.rename_column table_name, tmp_uuid_column_name, association_id_col
      rescue => e
        puts "Error: #{e} continuing"
        next
      end
    end

    # Make each temp _uuid column linked up
    # eg. Message.find(1).room_uuid = Message.find(1).room.uuid
    puts "[UPDATE] #{model}.uuid to association uuid"
  end

  ## Migrate primary keys to uuids
  table_names.each do |table_name|
    if ActiveRecord::Migration.column_exists?(table_name, :id) && ActiveRecord::Migration.column_exists?(table_name, :uuid)
      ActiveRecord::Base.connection.execute %Q{ALTER TABLE #{table_name} DROP CONSTRAINT #{table_name}_pkey CASCADE} rescue nil
      ActiveRecord::Migration.remove_column(table_name, :id)
      ActiveRecord::Migration.rename_column( table_name, :uuid, :id) if ActiveRecord::Migration.column_exists?(table_name, :uuid)
      ActiveRecord::Base.connection.execute "ALTER TABLE #{table_name} ADD PRIMARY KEY (id)"
      ActiveRecord::Base.connection.execute %Q{DROP SEQUENCE IF EXISTS #{table_name}_id_seq CASCADE} rescue nil
    end
  end
end

# Add uuid to the id
# EG. column_name_to_uuid("room_id") => "room_uuid"
# EG. column_name_to_uuid("room_ids") => "room_uuids"
def column_name_to_uuid(column_name)
  *a, b = column_name.split("_id", -1)
  a.join("_id") + "_uuid" + b
end
0
Mark Kuczmarski