rails41_jsonb.rb

Rails.application.config.after_initialize do
  ActiveSupport.on_load(:active_record) do
    oid = ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::OID

    # https://github.com/rails/rails/blob/v4.2.3/activerecord/lib/active_record/connection_adapters/postgresql/oid/jsonb.rb
    oid::Jsonb = Class.new(oid::Json) do
      def type
        :jsonb
      end

      def changed_in_place?(raw_old_value, new_value)
        # Postgres does not preserve insignificant whitespaces when
        # round-tripping jsonb columns. This causes some false positives for
        # the comparison here. Therefore, we need to parse and re-dump the
        # raw value here to ensure the insignificant whitespaces are
        # consistent with our encoder's output.
        raw_old_value = serialize(deserialize(raw_old_value))
        super(raw_old_value, new_value)
      end
    end

    oid.alias_type('jsonb', oid::Jsonb)

    # apply on models:
    require 'sequel'
    patch_model = lambda do
      db = Sequel.connect(ENV['DATABASE_URL'])
      db.select(:table_name, :column_name).
         from(:information_schema__columns).
         where(:data_type => 'jsonb',
               :column_default => "'{}'::jsonb").all.each do |h|
        Object.const_get(h[:table_name].classify).
          serialize(h[:column_name], JSON)
      end
    end

    patch_model.call

    # fix rails auto-reloading
    if Rails.configuration.cache_classes == false
      ActionDispatch::Reloader.to_prepare(&patch_model)
    end
  end
end