#177 Model Versioning

Aug 31, 2009 | 9 minutes | Active Record, Plugins

If you need to keep track of a model's history of changes and switch between versions, consider using the vestal_versions gem like I show in this episode.

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          bash
        
sudo rake gems:install
script/generate vestal_versions_migration
script/generate migration version_existing_pages
rake db:migrate

          config/environment.rb
        
config.gem 'laserlemon-vestal_versions', :lib => 'vestal_versions', :source => 'http://gems.github.com'

          models/page.rb
        
class Page < ActiveRecord::Base
  versioned
end

# version_existing_pages migration
say_with_time "Setting initial version for pages" do
  Page.find_each(&:touch)
end

          pages_controller.rb
        
def show
  @page = Page.find(params[:id])
  @page.revert_to(params[:version].to_i) if params[:version]
end

          script/console
        
p = Page.all
p.versions
p.revert_to(7.minutes.ago)
p.content
p.revert_to(:last)

          rhtml
        
<p>
  <%= link_to "Edit", edit_page_path(@page) %>
  | Version <%= @page.version %>
  <% if @page.version > 1 %>
    | <%= link_to "Previous version", :version => @page.version-1 %>
  <% end %>
  <% if params[:version] %>
    | <%= link_to "Latest version", :version => nil %>
  <% end %>
</p>