ActionView::Helpers::FormOptionsHelper

Provides a number of methods for turning different kinds of containers into a set of option tags.

Options

The collection_select, country_select, select, and time_zone_select methods take an options parameter, a hash.

• :include_blank - set to true or a prompt string if the first option element of the select element is a blank. Useful if there is not a default value required for the select element.

For example,

 select("post", "category", Post::CATEGORIES, {:include_blank => true}) 

could become:

 <select name="post[category]"> <option></option> <option>joke</option> <option>poem</option> </select> 

Another common case is a select tag for an belongs_to-associated object.

Example with @post.person_id => 2:

 select("post", "person_id", Person.find(:all).collect {|p| [ p.name, p.id ] }, {:include_blank => 'None'}) 

could become:

 <select name="post[person_id]"> <option value="">None</option> <option value="1">David</option> <option value="2" selected="selected">Sam</option> <option value="3">Tobias</option> </select> 

• :prompt - set to true or a prompt string. When the select element doesn’t have a value yet, this prepends an option with a generic prompt — "Please select" — or the given prompt string.

Example:

 select("post", "person_id", Person.find(:all).collect {|p| [ p.name, p.id ] }, {:prompt => 'Select Person'}) 

could become:

 <select name="post[person_id]"> <option value="">Select Person</option> <option value="1">David</option> <option value="2">Sam</option> <option value="3">Tobias</option> </select> 

Like the other form helpers, select can accept an :index option to manually set the ID used in the resulting output. Unlike other helpers, select expects this option to be in the html_options parameter.

Example:

 select("album[]", "genre", %w[rap rock country], {}, { :index => nil }) 

becomes:

 <select name="album[][genre]" id="album__genre"> <option value="rap">rap</option> <option value="rock">rock</option> <option value="country">country</option> </select> 

actionpack/lib/action_view/helpers/form_options_helper.rb