Question

I am trying to provide undo functionality after a record has been deleted. To do this, before I delete the record I clone it and put it in the session like so:

session[:undo] ||= []
session[:undo] << record.clone

however when I later do

rec = session[:undo][-1]
rec.save!

The record is not saved. The server console output says

(0.2ms)  BEGIN
[paperclip] Saving attachments.
(0.2ms)  COMMIT

which makes me think it is saved, but its not in the db. I am very confused. Any ideas?

Answer 1

A more stable way of doing this is to have an “active” boolean flag in the database that defaults to true. When you delete a record, just change that flag to false. To undo you just change it back to true.

# models/attachment.rb
class Attachment < ActiveRecord::Base
  default_scope where(:active => true)

  def self.include_inactive
    unscoped
  end
end

# in your migration
def self.up
  change_table :attachments do |t|
    t.boolean :active, :default => true, :null => false
  end

  add_index :attachments, :active
end

The self.include_inactive method is really just for clarity. It is really just an alias of unscoped, which will reset the default_scope that is ignoring deleted records. If you want to, for example, show all records in an admin dashboard, you can call Attachment.include_inactive.

Also note the index on the active column. Since most queries will include a where 'active' = 1 it is smart to ensure your database has this information easily accessible.