Auditing models with user_stamp

Cameron — Fri, 24 Oct 2008 09:39:01 +0000

As part of a CMS I’m building I wanted the ability to audit user interaction with data, to prevent the situation where content is being created, deleted or edited with no record of who did what and when.

John Nunemaker recently released his User Stamp plug-in which stamps records with the ID of the users that created and last updated. The implementation is quite clever, as he’s managed to work around the usual hack of storing the current user ID in Thread.current to make it accessible to the model by using a Sweeper, as they have access to controllers (and hence the current_user method).

I’ve taken his code a bit further by creating a Log model which stores a polymorphic reference to the record affected, the event that occurred (e.g. ‘deleted’ or ‘updated’), the current user ID and the time it happened.

The Log model;

class Log < ActiveRecord::Base
 
  # Relationships
  belongs_to :user
  belongs_to :loggable, :polymorphic => :true
 
  # Validations
  validates_presence_of :loggable_type
  validates_presence_of :loggable_id
  validates_presence_of :action
  validates_presence_of :user
 
end

The migration;

class CreateLogs < ActiveRecord::Migration
  def self.up
    create_table :logs do |t|
      t.string :loggable_type
      t.integer :loggable_id
      t.string :action
      t.references :user
      t.timestamps
    end
    add_index :logs, :loggable_id
    add_index :logs, :user_id
  end
 
  def self.down
    drop_table :logs
  end
end

Additional callback methods added to UserStampSweeper;

  def after_create(record)
    add_log(record, 'created')    
  end
 
  def after_update(record)
    add_log(record, 'updated')    
  end
 
  def after_destroy(record)
    add_log(record, 'delete')    
  end
 
  private
  def add_log(record, action)
    Log.create(
      :loggable_type => record.class.to_s, 
      :loggable_id => record.id, 
      :action => action, 
      :user => current_user
    )
  end

Displaying the logs;

<% for log in @logs %>
  
    <%= link_to (h log.loggable.log_name), [:admin, log.loggable] %>
    <%= h log.loggable_type %>
    <%= h log.action %>
     <%= link_to (h log.user.display_name), [:admin, log.user] %>
    <%= log.created_at.to_s %>
  
<% end %>

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Auditing models with user_stamp