NoMethodError：未定义方法“needs_migration？”对于 ActiveRecord::Migrator:Class

我收到以下错误消息，不知道如何解决它。有人可以帮忙吗？

NoMethodError：未定义方法“needs_migration？”为了 ActiveRecord::迁移器:类

这是 config.ru 代码：

require './config/environment'

if ActiveRecord::Migrator.needs_migration?
  raise 'Migrations are pending. Run `rake db:migrate` to resolve the issue.'
end

use Rack::MethodOverride

use UsersController
use ArtworkController
run ApplicationController

将您的代码更改为

if ActiveRecord::Base.connection.migration_context.needs_migration?
  raise 'Migrations are pending. Run `rake db:migrate` to resolve the issue.'
end