Collection_select not selecting item, unless

I’m fairly new to Rails, so this could just be my stupidity rather than

My app has two simple models: record (id, category_id, …) and
category (id, name). In my generated scaffold _form.html for the
record model, I have the following collection_select:

<%= collection_select ‘record’, ‘category’, @categories, :id, :name %>

The option tag is properly populated, but the current category for the
record being edited is not selected. However, if I change the above
line to:

<%= collection_select ‘record’, ‘category_id’, @categories, :id, :name

Then it will select the proper category in the HTML form. But, when I
try to save, it fails with an exception (ActiveRecord::RecordNotFound
in RecordsController#update => “Couldn’t find Category without an

Here’s the edit and update methods from RecordsController:

def edit
user = User.find(session[:user_id])
@record = user.records.find(params[:id])
@categories = user.categories.find(:all, :order => ‘name’)

def update
user = User.find(session[:user_id])
@record = user.records.find(params[:id])
# Replace the category id with the actual Category.
params[:record][:category] =
if @record.update_attributes(params[:record])
flash[:notice] = ‘Record was successfully updated.’
redirect_to :action => ‘show’, :id => @record
render :action => ‘edit’

Any ideas what I’m doing wrong?



P.S. You can browse all of my marvelous code here: => click on “manifest” and
you’ll see the typical Rails app structure.

If you change your collection select to “category_id”, you have to
change it in your controller too ofcourse, did you do that ?
so params[:record][:category] should be params[:record][:category_id]


Good point, that would address the error. Thanks.

However, the question remains: why do I have to change this to be
different than every single example of collection_select I have found
so far, including the AWDWR book, postings on this list, and the Rails
wiki itself?