Install

rake install

Merb

In the before the app loads block add:

dependency "sequel_versioned", "0.0.1" 

Sequel Plugin

Schema

Fact table needs to have the attribute lastest_version

The fact table needs for a versioned dimension both dimension_id and dimension_version attributes, the versioned dimension must have a fact_id.

For a versioned collection the fact table needs collection_version, and the collection objects must have a fact_id.

Model

The fact table needs to have a many_to_one association with each versioned dimension or collection.

To load the plugin in your Fact model

is(:versioned_fact, {:collections => [Collection], :dimensions => [Dimension]})  

Then in your versioned models is :versioned_dimension or is :versioned_collection depending on what you need.

The method version! is available on the fact model, along with fetch_dimension and fetch_collection.

Example

Say we have a blog posts and comments, all of which need to be versioned. So post would be our fact table, with post_detail as it's dimension. Each post would also have a versioned_collection of comments.

class Post < Sequel::Model
  set_schema do
    foreign_key :post_detail, :table => :post_details
  end
  
  is(:versioned_fact, {:collections => [Comment], :dimensions => [PostDetail]})  
  
  one_to_many :comments
  one_to_many :post_details

  def body
    fetch_post_detail.body
  end
end

The Post table would have to have the following fields defined: post_detail_id, post_detail_version, comments_version.

So when a new post is created a corresponding post_detail is also created.

To version the post and the comments, the method version! is provided on instances of the Post class.

class PostDetail < Sequel::Model
 set_schema do
   foreign_key :post_id, :table => :posts
 end
 is :versioned_dimension
 many_to_one :post
end

class Comments < Sequel::Model
 set_schema do
 foreign_key :post_id, :table => :posts
 end
 is :versioned_collection
 many_to_one :post
end

The comments and post_details table would have post_id and version defined.