Prompt in select_tag

In my application in user registration I have a country picker..

<%= select(:user, :country, options_for_select(@COUNTRIES)) %&开发者_运维百科gt;

And I want to add a prompt as a first default value (something like "--- select country ---"). Where and how should I put this option?

Use the FormHelper :prompt

select(:user, :country, options_for_select(@COUNTRIES), {:prompt => "--select county--"})

http://apidock.com/rails/ActionView/Helpers/FormOptionsHelper

collection_select(:product,
  :category_id,
  Category.all,    
  :id,    
  :title,    
  {:prompt => true}
)

collection_select(:product,    
  :category_id,    
  Category.all,    
  :id,    
  :title,    
  {:include_blank => 'Please Select'}
)

both of these result in the same html, but the first one will not include the 'Please Select' option when you return to edit the previously created Product

You can also give customized prompt value like this

select(:user, :country, options_for_select(@COUNTRIES), :prompt=>"select User name")

Very simple:

select(:user, :country, options_for_select(@COUNTRIES), :prompt=>true)

For the prompt "Please select", or this for your custom text:

select(:user, :country, options_for_select(@COUNTRIES), :prompt=>"Select country")

Also note that @COUNTRIES is wrong, an instance variable should be lowercase - @countries, a contant would just be COUNTRIES.