Sequel batch update

sequel_batch_update.rb

# Belongs in the dataset_module.
    #
    # Sample usage:
    #
    #   User.batch_update([[{full_name: "A"}, {full_name: "C"}], [{full_name: "B"}, {full_name: "D"}]])
    #   User.batch_update([[{id: 4}, {full_name: "C"}], [{id: 5}, {full_name: "D"}]])
    # 
    #   # Conditions will apply to all the updates.
    #   User.where { created_at < 1.month.ago }.qualify. 
    #     batch_update([[{id: 4}, {full_name: "C"}], [{id: 5}, {full_name: "D"}]])
    #
    # Came from conversation with Jeremy Evans: https://groups.google.com/g/sequel-talk/c/XJFkSuEiZBk
    def batch_update(data_lookup, return_sql: false, update_prefix: "set_")
      if data_lookup.present?
        lookup_columns, update_columns = data_lookup.first.map(&:keys)
        add_update_prefix = -> (str) { :"#{update_prefix}#{str}" }
        from, to = Sequel[:data], Sequel[first_source]
        conditions = lookup_columns.each.with_object({}) { |col, h| h[to[col]] = from[col] }
        updates    = update_columns.each.with_object({}) { |col, h| h[col] = from[add_update_prefix[col]] }
        values = data_lookup.map { |l, u| l.values + u.values }

        from(
          to.value.to_sym,
          db.values(values).as(from.value.to_sym, [*lookup_columns, *update_columns.map(&add_update_prefix)])
        ).
          where(conditions).
          send(return_sql ? :update_sql : :update, updates)
      else
        return_sql ? nil : 0
      end
    end