Does acts_as_attachment :storage => :db_system work?

I found the post about needing to install acts_as_attachement_1_1_6 if
you are not on edge rails. But I am having trouble getting db_system
storage to work. As far as I can tell in from the database, things are
working, but I don't see how my model table hooks up with the db_files
table so I am having trouble altering the image_tag from the tutorial
(http://weblog.techno-weenie.net/articles/acts_as_attachment) so that
it pulls data from the database. (Everything works fine if I want to
use :storage => :file_system)

How are my generated model and db_files connected? and what do I need
in my show action to send the image to the browser? I tried code like
this:

    send_data @picture.data_file.data, :filename => @picture.filename,
:type => @picture.content_type, :dispo\
sition => 'inline'

But I get an undefined method error for data_file, which doesn't
surprise me since I don't see any link between the db_files table and
my pictures table. Parent_id could have been it, but a) it is blank
and b) the docs seem to indicate that is used mainly for keeping track
of which images are just resized versions of other images.

TIA

    send_data @picture.data_file.data, :filename => @picture.filename,
:type => @picture.content_type, :dispo\
sition => 'inline'

Shouldn't that be db_file, not data_file?

> send_data @picture.data_file.data, :filename => @picture.filename,
> :type => @picture.content_type, :dispo sition => 'inline'

Shouldn't that be db_file, not data_file?

OOps. yes. But that just gets me to a different error message:

  You have a nil object when you didn't expect it!
  The error occured while evaluating nil.data

And while trying to double check that I had not messed anything up, I
am reminded that to get
as far as I did, I had had to comment out another piece of code that
was causing errors. So for a full recap:

I have Rails 1.1.6 installed on a RHEL 4 system running ruby 1.8.4
(installed from source). I installed acts_as_attachment using the
command "script/plugin install
http://svn.techno-weenie.net/projects/plugins/tags/acts_as_attachment-1.1.6"
If I set the DB environment variable, running the test "rake
test_plugins PLUGIN=acts_as_attachment" seems to work - but I had
expected more output - such as a list of # of tests and # passed.

If I set my Picture model up to use :storage => :file_system, all
seems to work just fine. To try to use :db_system, I needed to
uncomment the lines about db_file before running the migration built
when I did "script/generate attachment_model picture". Then I set up
my model up like:

class Picture < ActiveRecord::Base
  acts_as_attachment :storage => :db_system, :max_size =>
500.kilobytes, :content_type => :image
  validates_as_attachment
end

and my controller like this:

class PictureController < ApplicationController
  def index
    @pictures = Picture.find(:all)
  end

  def new
    @picture = Picture.new
  end

  def show
    @picture = Picture.find(params[:id])
    send_data @picture.db_file.data, :filename => @picture.filename,
:type => @picture.content_type, :disposition => 'inline'
  end

  def create
    @picture = Picture.create params[:picture]
    redirect_to :action => 'show', :id => @picture
  rescue ActiveRecord::RecordInvalid
    render :action => 'new'
  end
end

When I try to upload a new image, I can see the following exception:

undefined method `db_file_id=' for #<Picture:0xb77f83fc>

RAILS_ROOT: /rails/admissions/script/../config/..
Application Trace | Framework Trace | Full Trace

/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/base.rb:1789:in
`method_missing'
#{RAILS_ROOT}/vendor/plugins/acts_as_attachment-1.1.6/lib/technoweenie/acts_as_attachment.rb:316:in
`save_to_storage'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/callbacks.rb:333:in
`callback'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/callbacks.rb:330:in
`callback'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/callbacks.rb:248:in
`create_or_update'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/base.rb:1392:in
`save_without_validation'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/validations.rb:724:in
`save_without_transactions'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactions.rb:126:in
`save'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/connection_adapters/abstract/database_statements.rb:51:in
`transaction'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactions.rb:91:in
`transaction'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactions.rb:118:in
`transaction'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/transactions.rb:126:in
`save'
/software/stow/ruby-1.8.4/lib/ruby/gems/1.8/gems/activerecord-1.14.3/lib/active_record/base.rb:408:in
`create'
#{RAILS_ROOT}/app/controllers/picture_controller.rb:16:in `create'

In the module DbFileMethods section of acts_as_attachment.rb, I
commented out the line that calls db_file_id= and then I can upload
files. I see the insert statements for both db_files and pictures and
looking in the database, I see roughly the data I expect (Can't easily
inspect the image from the terminal, but it is of the same length as
the length stored in pictures.size. But when I try to use the show
method above, I get the nil.data error at the top of this post. And I
am having trouble working backwards from the only code that seems it
ties pictures to db_files to the syntax I need in my show controller
so I can display the images right out of the database. Is this the
code that tells the the two tables they are related?

    module DbFileMethods def self.included(base) #:nodoc:
        base.belongs_to :db_file
        base.before_save :save_to_storage # so the db_file_id can be set
      end

And I would have expected one or the other table to have a foreign
key. What am I missing?

undefined method `db_file_id=' for #<Picture:0xb77f83fc>

That means you're missing the db_file_id row. This points your
attachment to the row in the db_files table. Removing the part that
sets this in the plugin means the two are never attached.

Thanks Rick. I added the column to my created table and now everything
works. Can I ask that you patch
acts_as_attachment-1.1.6/generators/attachment_model/templates/migration.rb
to have the following lines somewhere within the create table
definition:

      # uncomment this before migrating if you want db-based files
      # t.column "db_file_id", :integer

Thanks. Great product, now that you showed me the trick to making
db_system work.