selected values are resetting in page reload in ruby on rails

Question

Iam new to ruby on rails.I want to show the selected values from drop down and checked radio button in page reload. When the page is reloaded, the selected value of the drop down and radio button are getting reset.So please let me know how to fix this issue.Here is the code i'am using.

    <%= form_tag :action => 'show' do%>
<strong>Select device: </strong> <%= collection_select(:device, :id, @devices, :id, :name, options ={:prompt => "-Select a device"}) %>
<br></br>
<strong>Chose:</strong><%=  radio_button_tag :name,:time, false, :onclick => "this.parentNode.submit();"%>Time
<%=  radio_button_tag :name,:graph%>Graph
<% end %>

Answer 1

Try:

 collection_select(:device, :id, @devices, :id, :name, {:selected => @your_selected_value, :prompt => "-Select a device"})

see radio_button_tag(name, value, checked = false, options = {})

<%=  radio_button_tag :name,:time, @your_checked_value.eql?('time'), :onclick => "this.parentNode.submit();"%>Time
<%=  radio_button_tag :name,:graph, @your_checked_value.eql?('graph') %>Graph