Selecting all values from list

gistfile1.rb

  	  <% form_tag @maps, :method => 'get' do %>
		   <label>Campaign Id:</label>
	  
    <%= select_tag "campaign_id", options_from_collection_for_select(@campaign, "id", "title" ,prompt="all")  %>
      <label for="from">From</label>
	  
    <%= text_field_tag :from, @from.strftime("%d-%m-%Y") || Date.today.beginning_of_month.strftime("%d-%m-%Y")%>
    <label for="to">to</label>
    <%= text_field_tag :to, @to.strftime("%d-%m-%Y") || Date.today.end_of_month.strftime("%d-%m-%Y") %>
    <%= submit_tag "Update" %>
  <% end %>