# File lib/rails-installer.rb, line 506
  def pre_migrate_database
    old_schema_version = get_schema_version
    new_schema_version = File.read(File.join(source_directory,'db','schema_version')).to_i
    
    return unless old_schema_version > 0
     
    # Are we downgrading?
    if old_schema_version > new_schema_version
      message "Downgrading schema from #{old_schema_version} to #{new_schema_version}"
      
      in_directory install_directory do
        unless system("rake -s migrate VERSION=#{new_schema_version}")
          raise InstallFailed, "Downgrade migrating from #{old_schema_version} to #{new_schema_version} failed."
        end
      end
    end
  end