Rails - Feb 2006 - Question about re-using entry form when a validation error occurs

Hi,

I think I may be doing more work than necessary. I have a form that is
used in both my "New" and "Edit" pages (originally created
by a
scaffold.)

In my form, I have several popups that I have to populate, and if on
the Edit page, selects the appropriate entry.

To build the popup menus, I''m using:
  <%= options_from_collection_for_select(@teams, "id",
"number",
@match_teams[0]) %>

@teams is set in the controller New method:
  @teams = Team.find(:all, :order => "number")

and I have to set @match_teams to "".

In the Edit method, I again have to set the @teams variable (no
problem), and I then set the @match_teams array like:

    @match_teams = []
    @match.competitions.each do |team|
      @match_teams << team.team_id
    end

That''s fine. Except if the user enters an incorrect value into a field
(no duplicate "match" numbers, for example). The "Create"
method does:
  if @match.save
  ....
  else
     render :action => ''new''  #error occured, re-display
the form
  end

However, when that happens, I get an error about having a null
variable on my form, in the first call to
''options_from_collection_for_select'' - since @teams and
@match_teams
is null.

So now I have to do:
     @teams = Team.find(:all, :order => "number")
      @match_teams = []
      params[:Red].each do |t|
        @match_teams << t.to_i
      end
      params[:Blue].each do |t|
        @match_teams << t.to_i
      end

      render :action => ''new''

(pulling the user set values out of the form to re-set up the items).
And I realized I have to do the same thing in the "Update" method (if
it fails due to a validation fault.)

Am I missing something? Should the @teams and @match_teams variables
persist? Sure I can factor the similar code to its own method, but it
seems like a lot of extraneous work.

Thanks for any help / hints.

jt