select_tag 选择后自动提交，并且保持选择的项

使用select来选择，，，选择就响应真是花了好大的功夫。。。。你妹。。。在controller设置变量来储存选择后的值。。。js中如果select选择为空那么传入的值是””而不是null

selectedIndex的值都是数字，从0开始，而不是option的值

controller

#sdn的网络流量监控

  def monitor

    @vms = VirtualMachine.owned_by(current_user).select('*').joins("left join vnets on virtual_machines.vnet_id = vnets.id").where("vnets.net_type = 'sdn'")

    @switches = [["second","_10seconds"],["minute","_5minutes"],["hour","_hour"],["day","_day"],["week","_week"],["month","_month"],["year","_year"]]

    @ccs = [["",""],["",""],["",""],["",""],["",""],["",""],["",""],["",""],["",""],["",""]]

    @jiange_value = params[:times]

    @col_value = params[:col]

    @lscol = @col_value.to_i

    id_hash = Hash.new

    id_hash["_10seconds"] = ""

    id_hash["_5minutes"] = ""

    id_hash["_hour"] = ""

    id_hash["_day"] = ""

    id_hash["_week"] = ""

    id_hash["_month"] = ""

    id_hash["_year"] = ""

    @lsjiange = id_hash[@jiange_value]

  End

monitor.html.erb

<%= render partial: 'vnet_nav_bar' %>

<meta charset="utf-8">

<head>

  <script>

    window.onload = initForm;

    function initForm()

    {

      //alert("<%= @lsjiange %>");

      document.getElementById('col').selectedIndex = <%= @lscol %>

      document.getElementById('times').selectedIndex = <%= @lsjiange %>

      document.getElementById("col").onchange = popu;

      document.getElementById("times").onchange = popu;

    }

    function popu()

    {

        //alert("bb");

        var form1 = document.getElementById("idform");

        form1.submit();

        var c = document.getElementById('col').selectedIndex;

        //alert(c);

    }

  </script>

</head>

<%= form_tag("monitor",:id => "idform",name: "idform") do |f| %>

  <%= select_tag "times", options_for_select(@switches),prompt: "选择间隔>时间" %>

  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  <%= select_tag "col", options_for_select(@ccs), prompt: "选择列数" %>

  &nbsp;&nbsp;&nbsp;

  <%= submit_tag("刷新") %>

  <% columns = @col_value.to_i %>

  <% if columns == 0 %>

  <% columns = 2 %>

  <% if columns == 0 %>

  <% columns = 2 %>

  <% end %>

  <% if @jiange_value == "" %>

  <% @jiange_value = "_5minutes"%>

  <% end %>

  <% rows = @vms.size/columns %>

  <% unless (@vms.size%columns)==0 %>

  <% rows = rows + 1 %>

  <% end %>

  <% vmid = 0 %>

  <center>

    <table>

        <% for i in 0..rows-1 do %>

          <tr>

          <% for j in 0..columns-1 do %>

            <td>

            <% if @jiange_value.nil? %>

            <% @jiange_value = '_5minutes' %>

            <% end %>

            <%= image_tag("rrdtool/#{@vms[vmid].uuid}#{@jiange_value}.png") %>

            <% vmid = vmid + 1 %>

            </td>

            <% if vmid >= @vms.size %>

            <% break %>

            <% end %>

          <% end %>

          </tr>

        <% end %>

    </table>

  </center>

<% end %>

select_tag 选择后自动提交，并且保持选择的项