## rails generator
<%= collection_select(:project, :project_id, @projects, :name, :name)  %>

## html generated
<select id="project_project_id" name="project[project_id]">
<option value="Tennessee">Tennessee</option>
</select>

## ajax observer
<%= observe_field 'project_project_id', :function => "alert('bam')" %>

## generated ajax
//<![CDATA[
new Form.Element.EventObserver('project_project_id', function(element, value) {alert('bam')})
//]]>


## error
element is null
getValue(null)prototype.js?1208... (line 3517)
getValue()prototype.js?1208... (line 3706)
initialize("project_project_id", function())prototype.js?1208... (line 3670)
klass()prototype.js?1208... (line 48)
new()new (line 24)
[Break on this error] var method = element.tagName.toLowerCase();