Rails custom query data export

I am trying to export the data through rails to excel, but have a slight problem. When you go to the show.html.erb, it automatically displays the last 24 records from Reviews table. I have datetime selector on the same page to query to get the data from Reviews table as per datetime lookup. Excel/CSV export works fine for the last 24 records, but as soon as I conduct custom query through datetime selector and click on Export to xls, I still get last 24 records exported. I pretty well understand that respond_to code refreshes the controller after query and it considers that params are blank, which is the reason I am always getting last 24 records exported.

I want to export the data after custom query (through datetime query).

Does this make sense? Your kind assitance will be appreciated.

My controller code: review_controller.rb

if params[:date_from].blank? && params[:date_to].blank?
  @data = Reviews.last(24).order(date_time: :desc)
elsif
  @date_from = params[:date_from]
  @date_to = params[:date_to]
  @data = Reviews.where("date_time >= ? AND date_time <= ?", @date_from, @date_to).order(date_time: :desc)
end
respond_to do |format|
  format.html
  format.csv { send_data @data.to_csv }
  format.xls { send_data @data.to_csv(col_sep: "\t") }
end
end

View: show.html.erb

<%= form_tag(review_path, :method => "get")  do %>
  <%= label_tag :date_from, 'From:' %>
  <%= text_field_tag :date_from, @date_from, :id => 'datetimepicker1' %>
  <%= label_tag :date_to, 'To:' %>
  <%= text_field_tag :date_to, @date_to, :id => 'datetimepicker2' %>
  <%= button_tag :Update, class: 'btn btn-info' %>
<% end %>`

Model: review.rb

def self.to_csv(options = {})
  CSV.generate(options) do |csv|
    csv << column_names
    all.each do |products|
      csv << products.attributes.values_at(*column_names)
    end
  end
end