gistfile1.rbx

# Released under WTFPL - http://sam.zoy.org/wtfpl/
module PoorMansMigrations
  @@_migration_columns = []

  def column(name, type, options = {})
    @@_migration_columns << {:column_name => name, :column_type => type, :options => options}
  end

  def realize!(force_drop = false)
    # Force drop if needed
    connection.drop_table(table_name) if force_drop && table_exists?
    
    # Create table
    connection.create_table(table_name) {|t| } unless table_exists?
    
    @@_migration_columns.each do |p|
      #haxhaxhax - Force reload reading column names. Whatever.
      reset_column_information
      column_exists = column_names.include?(p[:column_name].to_s)

      # Delete the columns if forced to
      if p[:options].delete(:force) && column_exists
        connection.remove_columns(table_name, p[:column_name])
        column_exists = false
      end

      connection.add_column(table_name, p[:column_name], p[:column_type], p[:options]) unless column_exists
    end
  end
  
  def clean_leftover_columns!
    return unless table_exists?
    reset_column_information
    
    left_overs = column_names - @@_migration_columns.map {|m| m[:column_name].to_s} - Array(primary_key)
    connection.remove_columns(table_name, left_overs)
  end
  
  # Force recreation for everything
  def migrate!
    realize!(true)
    clean_leftover_columns!
  end

  # Take it easy. Only force if specified in column definition
  def migrate
    realize!
    clean_leftover_columns!
  end
end

ActiveRecord::Base.send :extend, PoorMansMigrations