Readme.rdoc

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Last Update: Mon Aug 09 21:09:43 +0200 2010

Userstamp

Overview

Userstamp extends ActiveRecord::Base to add automatic updating of ‘creator’, ‘updater’, and ‘deleter’ attributes. It is based loosely on the ActiveRecord::Timestamp module.

Two class methods (model_stamper and stampable) are implemented in this plugin. The model_stamper method is used in models that are responsible for creating, updating, or deleting other objects. The stampable method is used in models that are subject to being created, updated, or deleted by ‘stampers’.

Installation

 - As Rails plugin: `script/plugin install git://github.com/delynn/userstamp.git `
 - As gem: ` sudo gem install userstamp `

Usage

The assumption is that you have two different categories of objects; those that manipulate, and those that are manipulated. For those objects that are being manipulated there‘s the Stampable module and for the manipulators there‘s the Stamper module. There‘s also the actual Userstamp module for your controllers that assists in setting up your environment on a per request basis.

Example

Assume a weblog application has User and Post objects. # 1: Create the migrations for these objects

  class CreateUsers < ActiveRecord::Migration
    def self.up
      create_table :users, :force => true do |t|
        ...
        t.userstamps # use t.userstamps(true) if you also want 'deleter_id'
      end
    end

    def self.down
      drop_table :users
    end
  end

  class CreatePosts < ActiveRecord::Migration
    def self.up
      create_table :posts, :force => true do |t|
        ...
        t.userstamps # use t.userstamps(true) if you also want 'deleter_id'
      end
    end

    def self.down
      drop_table :posts
    end
  end

# 2: Users are going to manipulate Post‘s, use the model_stamper:

  class User < ActiveRecord::Base
    model_stamper
  end

# 3: Set the current user in the ApplicationController:

  class ApplicationController < ActionController::Base
    include Userstamp
  end

If all you are interested in is making sure all tables that have the proper columns are stamped by the currently logged in user you can stop right here. More than likely you want all your associations setup on your stamped objects, and that‘s where the stampable class method comes in. So in our example we‘ll want to use this method in both our User and Post classes:

  class User < ActiveRecord::Base
    model_stamper
    stampable
  end

  class Post < ActiveRecord::Base
    stampable
  end

Okay, so what all have we done? The model_stamper class method injects two methods into the User class. They are stamper= and stamper and look like this:

  def stamper=(object)
    object_stamper = if object.is_a?(ActiveRecord::Base)
      object.send("#{object.class.primary_key}".to_sym)
    else
      object
    end

    Thread.current["#{self.to_s.downcase}_#{self.object_id}_stamper"] = object_stamper
  end

  def stamper
    Thread.current["#{self.to_s.downcase}_#{self.object_id}_stamper"]
  end

The stampable method allows you to customize what columns will get stamped, and also creates the creator, updater, and deleter associations.

The Userstamp module that we included into our ApplicationController uses the setter method to set which user is currently making the request. By default the ‘set_stampers’ method works perfectly with the RestfulAuthentication plug-in:

  def set_stampers
    User.stamper = self.current_user
  end

If you aren‘t using ActsAsAuthenticated, then you need to create your own version of the set_stampers method in the controller where you‘ve included the Userstamp module.

Now, let‘s get back to the Stampable module (since it really is the interesting one). The Stampable module sets up before_* filters that are responsible for setting those attributes at the appropriate times. It also creates the belongs_to relationships for you.

If you need to customize the columns that are stamped, the stampable method can be completely customized. Here‘s an quick example:

  class Post < ActiveRecord::Base
    stampable :stamper_class_name => :person,
              :creator_attribute  => :create_user,
              :updater_attribute  => :update_user,
              :deleter_attribute  => :delete_user
  end

Upgrade from 1.x

 # config/environment.rb
 Ddb::Userstamp.compatibility_mode = true

Example userstamp application

Running Unit Tests

 All: rake
 One: ruby test/compatibility_stamping_test.rb

Author

DeLynn Berry

The original idea for this plugin came from the Rails Wiki article entitled Extending ActiveRecord.

Contributors / maintenance / enhancement

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