Question

我有一个购买模型has_one 优惠券。

购买模型包含以下代码：

def decrement_coupon
  coupon = Coupon.find_by_code(coupon_code, :readonly => false)
  return unless coupon.respond_to?(:uses)
  coupon.uses = coupon.uses - 1
  coupon.save
end

但是前几天我收到了这个错误：

ActiveRecord::ReadOnlyRecord - ActiveRecord::ReadOnlyRecord:
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/persistence.rb:245:in `create_or_update'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/callbacks.rb:273:in `create_or_update'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activesupport-3.0.6/lib/active_support/callbacks.rb:419:in `_run_save_callbacks'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/callbacks.rb:273:in `create_or_update'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/persistence.rb:39:in `save'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/validations.rb:43:in `save'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/attribute_methods/dirty.rb:21:in `save'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:240:in `save'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:292:in `with_transaction_returning_status'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/connection_adapters/abstract/database_statements.rb:139:in `transaction'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:207:in `transaction'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:290:in `with_transaction_returning_status'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:240:in `save'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:251:in `rollback_active_record_state!'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/transactions.rb:239:in `save'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/associations/association_proxy.rb:222:in `send'
 /usr/local/rvm/gems/ree-1.8.7-2010.02@lyconic/gems/activerecord-3.0.6/lib/active_record/associations/association_proxy.rb:222:in `method_missing'
 /var/www/88tactical_production/releases/20110823232510/app/models/purchase.rb:69:in `decrement_coupon'

:readonly => false不保证非读取记录吗？将此功能移至优惠券模式会有所作为吗？（无论如何，我可能会这样做）

Answer 1

这可能是由于您通过find_by_code（）帮助程序加入其他子值。

当ActiveRecord使用连接查找返回其他值的对象时，它会将记录标记为只读。

这里有关于这个问题的详细描述：

What is causing this ActiveRecord::ReadOnlyRecord error?

如果是这种情况，您可以通过将：加入转换为正确的：include 来填充ActiveRecord实例而不标记它们，从而解决问题。仅

这段代码如何抛出ActiveRecord :: ReadOnlyRecord异常？

1 个答案: