collection_select default value?

I'm having some confusion with collection_select(). I am using two
of them on my form:

<%= collection_select(:user, :id, @users, :id, :login) %>
<%= collection_select(:department, :id, @depts, :id, :name, {},
:multiple=>"multiple") %>

If I submit the page without selecting a department in the multiselect
box, I will get a nil object. This is what I want.

If I submit the page without selecting a user, I do not get a nil user
object. It is populated with the first item in the select box. This
is not what I want. I want to detect that a user has not selected a
name from the list.

Why is the first collection_select() returning a value when the user
has not selected an item?

Thx,

Gary H.

You have two options for this:
1) <%= collection_select(:user, :id, @users, :id, :login,
{:include_blank => true}) %> to show a blank option
OR
2) <%= collection_select(:user, :id, @users, :id, :login, {:promt =>
'Select a user'}) %> to show a default text

Hope this helps