Working with Rails' select_tag helper to build a search form, I needed to retain the user's selected value after a form get, and was using the options_for_select helper:

# Doesn't retain value
<%= select_tag 'search[status]',
options_for_select([['- All -', nil]] + Settings[:states].collect { |name, id| [name.to_s.titlecase, id] },
params[:search][:status]) %>

Whenever the form was posted, the select popup would always revert to its default value.

The reason? params[:search][:status] is by default a String, whereas the option values are integers, and so don't match ("1" != 1). The simple fix is to convert it to an integer using to_i:

# Convert the given params[:search][:status] to an integer using to_i
<%= select_tag 'search[status]', 
options_for_select([['- All -', nil]] + Settings[:states].collect { |name, id| [name.to_s.titlecase, id] }, 
params[:search][:status].to_i) %>

Update: Fixed missing bracket in code (25 May 2009)