submit-social-housing-lettings-and-sales-data/db/migrate/20240108152935_unread_migration.rb

class UnreadMigration < ActiveRecord::Migration[6.0]
  def self.up
    create_table ReadMark, force: true, options: create_options do |t|
      t.references :readable, polymorphic: { null: false }
      t.references :reader,   polymorphic: { null: false }
      t.datetime :timestamp, null: false
    end

    add_index ReadMark, [:reader_id, :reader_type, :readable_type, :readable_id], name: 'read_marks_reader_readable_index', unique: true
  end

  def self.down
    drop_table ReadMark
  end

  def self.create_options
    options = ''
    if defined?(ActiveRecord::ConnectionAdapters::Mysql2Adapter) \
      && ActiveRecord::Base.connection.instance_of?(ActiveRecord::ConnectionAdapters::Mysql2Adapter)
      options = 'DEFAULT CHARSET=latin1'
    end
    options
  end
end