Grouped Select in Rails

Question

Simple question really - how do I use the select(ActionView::Helpers::FormOptionsHelper) with grouped options?

I have got it working with a select_tag (ActionView::H

Answer 1

Edit

Correction, since you're using Arrays you'll need grouped_options_for_select

Example:

grouped_options = [
  ['Group 1',
    ["Item 1", "Item 2", "Item 3"]],
  ['Group 2',
    ["Item 1", "Item 2", "Item 3", "Item 4"]]
]
grouped_options_for_select(grouped_options)

Prints the following:

<optgroup label="Group 1">
  <option value="Item 1">Item 1</option>
  <option value="Item 2">Item 2</option>
  <option value="Item 3">Item 3</option>
</optgroup>
<optgroup label="Group 2">
  <option value="Item 1">Item 1</option>
  <option value="Item 2">Item 2</option>
  <option value="Item 3">Item 3</option>
  <option value="Item 4">Item 4</option>
</optgroup>

Note that you have to provide your own select tags to wrap this. There is no select function that will do grouping for you, just this method.

You should get over your reticence. The Rails Way (tm) to do what you ask is to use select_tag with grouped_options_for_select:

<%= select_tag "foo[bar]", 
grouped_options_for_select(@bars) %>

This is what happens when you go off the beaten path with Rails. :)

Here's a reference I just found on google:

http://www.ruby-forum.com/topic/185407

Answer 2

You can also use a Hash instead of nested arrays:

grouped_options = {
 'North America' => [['United States','US'], 'Canada'],
 'Europe' => ['Denmark','Germany','France']
}


<%= select_tag "foo[bar]", 
grouped_options_for_select(grouped_options, 'Denmark') %>

Here, there is also a selected option ('Denmark')