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上before_create,before_update,before_destroy方法,我想这样做的,如果:在多个约束,如before_create:方法中,如果:[:多个:约束]
before_destroy :lock_quantity, if: [:processed, :quantity_changed]
,这样,如果它已经处理量不能改变
(以防万一:)
def lock_quantity
errors.add :quantity, "You must revert the row before changing quantity"
end
如此,才可能有多个条件: ?