before_create :方法，if：[:multiple，:constraints]

Question

在before_create、before_update、before_destroy方法上，我想对多个约束执行if：，例如

before_destroy :lock_quantity, if: [:processed, :quantity_changed]

所以如果它被处理了，数量就不能改变

(以防万一：)

def lock_quantity
  errors.add :quantity, "You must revert the row before changing quantity"
end

那么，if：？可以有多个条件吗？

Answer 1

所以实际上应该是这样的.

before_update :lock_quantity, if: [:processed, :quantity_changed?]

注意这个问号！

(以防万一：)

def lock_quantity
  errors.add :quantity, "You must revert the row before changing quantity"
  false
end

传递false以停止保存