Question

我想运行一个跟踪CRUD内记录属性更改的方法，但只有当它们与Update操作一起保存时才会运行。我现在在模型中有这个：

before_save :check_changed
def check_changed
  puts "Period Contributions Changed? : #{period_contributions_changed?}"
  puts "Total Contributions Changed? : #{total_contributions_changed?}"
  puts "Period Expenditures Changed? : #{period_expenditures_changed?}"
  puts "Total Expenditures Changed? : #{total_expenditures_changed?}"
end

但这也是在创建新记录时运行的。我是否可以在check_changed方法中执行测试以确定是创建还是更新了记录？感谢

Answer 1

检查条件回调：if和：unless

before_save :check_changed, unless: :new_record?

或者你可以使用'new_record？'在你的方法

def check_changed

  return if new_record?

  puts "Period Contributions Changed? : #{period_contributions_changed?}"
  puts "Total Contributions Changed? : #{total_contributions_changed?}"
  puts "Period Expenditures Changed? : #{period_expenditures_changed?}"
  puts "Total Expenditures Changed? : #{total_expenditures_changed?}"
end

编辑：还应该结帐

after_save :check_changed, on: [:update]

文档为here

Rails：检查启动内存的方法：before_save

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