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Rake task to read and write the ActiveRecord schema version table.

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Posted On: January 31st, 2007 by kencollins

After attending Rails Edge in Reston, Virginia I decided to move some common tasks from my ~/.irbrc file and put them into Rake. I thought I would share a task that reads and writes the ActiveRecord schema table. Sometimes in migrations this is either good to know or manually change. Simply copy this in a foo.task file in your project/lib/tasks directory and use rake -T to see the description and usage. I have placed these tasks in the db:version namespace.

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namespace :db do
  namespace :version do 

    desc "Read the current version of the database."
    task :read => :environment do
      puts "The #{RAILS_ENV}' database version is: #{ActiveRecord::Migrator.current_version}"
    end
    
    desc "Manually set the schema version to a specific target version with VERSION=x"
    task :write => :environment do
      if ENV['VERSION']
        if ActiveRecord::Base.connection.update("UPDATE #{ActiveRecord::Migrator.schema_info_table_name} SET version = #{ENV['VERSION'].to_i}")
          puts "SUCCESS: The '#{RAILS_ENV}' database version is now: #{ActiveRecord::Migrator.current_version}"
        else
          puts "FAILED: The '#{RAILS_ENV}' database version is still: #{ActiveRecord::Migrator.current_version}"
        end
      else
        puts 'You must specify a VERSION=n argument to this command. Use rake db:version:read to get the current version.'
      end
    end
    
  end  
end