Rails - Feb 2006 - Example code for select_from_db (a.k.a. combo box)

I''m not asking for help this time!  :) :)  In almost every Rails  
project I create, I find that I want a select() popup menu that is  
pre-populated by data from the database.  Also, I want an "Other..."  
option that presents a text_field_tag to input another (not  
presented) option (basically a combo-box).  In an attempt to be as  
DRY as possible, I''ve come up with the following code for achieving  
that.  It works for me, but I wanted to see if any of y''all have any  
commentary on how this could be better done (and also I wish I could  
have found this when I was looking myself as an example of how this  
could be done, so here it is for others).

- Peter

P.S. My model is Asset and controller is Assets (obviously), change  
those instances below for your own model/controller names.


==== app/helpers/application_helper.rb ===
   def select_from_db(object, method, choices, options = {},  
html_options = {})

     results = Asset.find(:all) if choices.blank?

     if results
       choices = Array.new
       results.each do |result|
         unless result.send(method).blank?
           choices << result.send(method)
         end
       end
       choices = choices.sort.uniq
     end

     choices.insert(0,"") if options[:include_blank]
     choices << ["Other...","other"] if
options[:include_other]

     if options[:selected]
       selected = "#{options[:selected]}"
     else
       selected = ""
     end

     uniqid = "#{html_options[:uniqid]}" if html_options[:uniqid]
     tag = "#{object}_#{method}_#{uniqid}"

     output = Array.new

     output << tag(''div'',
       options          { :open => true },
       html_options          { :id => "#{tag}_div" })

     output << select_tag("#{tag}",
       options_for_select( choices, selected ))

     output << observe_field("#{tag}",
       :condition => "escape(value) != ''''",
       :url =>
         {
           :field => :select,
           :action => :updateform,
           :object => "#{object}",
           :method => "#{method}",
           :uniqid => "#{uniqid}"
         },
       :with => "''value=''+escape(value)")

     output << content_tag(''span'', '''',
       html_options          { :id => "#{tag}_status" })

     output << "</div>"

     output << tag(''div'',
       html_options          { :style => ''display: none;'',
:id => "#{tag}_other_div" })
     output << text_field_tag("#{tag}_other",
'''')

     output << observe_field("#{tag}_other",
       :condition => "escape(value) != ''''",
       :url =>
         {
           :field => :other,
           :action => :updateform,
           :object => "#{object}",
           :method => "#{method}",
           :uniqid => "#{uniqid}"
         },
       :with => "''value=''+escape(value)")

     output << content_tag(''span'', '''',
       html_options = { :id => "#{tag}_other_status" })

     output << "</div>"
   end


==== app/controllers/assets_controller.rb ===
   def updateform
     case params[:field]
     when "select"
       case params[:value]
       when "other"
         render :partial => "show_other", :locals => { :params
=>
@params }
       else
         render :partial => "hide_other", :locals => { :params
=>
@params }
       end

     when "other"
       render :partial => "hide_other", :locals => { :params
=>
@params }
     end
   end


==== app/views/assets/_show_other.rjs ===
tag = "#{params[:object]}_#{params[:method]}_#{params[:uniqid]}"

page << "if (Element.visible(''#{tag}_other_div'') ==
false)
Effect.SlideDown(''#{tag}_other_div'');"
page << "$(''#{tag}_other'').focus();"
page << "$(''submit'').disabled = true;"


==== app/views/assets/_hide_other.rjs ===
tag = "#{params[:object]}_#{params[:method]}_#{params[:uniqid]}"

if (params[:field] == "other")
   page.insert_html :bottom, "#{tag}", content_tag("option",
"#{params
[:value]}")
   page << "$(''#{tag}'').selectedIndex =
$(''#{tag}'').length-1;"
end
page << "if (Element.visible(''#{tag}_other_div''))
Effect.SlideUp(''#
{tag}_other_div'');"
page << "$(''submit'').disabled = false;"


==== app/views/assets/test.rhtml ===
<%=
select_from_db(''asset'',''head'','''',
options = { :include_blank =>
true, :include_other => true}, html_options = { :uniqid => "48"
}) %>
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