Maybe/app/controllers/transactions/bulk_updates_controller.rb

class Transactions::BulkUpdatesController < ApplicationController
  def new
  end

  def create
    updated = Current.family
                     .entries
                     .where(id: bulk_update_params[:entry_ids])
                     .bulk_update!(bulk_update_params)

    redirect_back_or_to transactions_path, notice: "#{updated} transactions updated"
  end

  private
    def bulk_update_params
      params.require(:bulk_update)
            .permit(:date, :notes, :category_id, :merchant_id, entry_ids: [], tag_ids: [])
    end
end