您所做的可能不是***的方法，因此也许有人可以用更好的方法回答。但是，要使您的生产线正常工作，您需要使其实际上保持更改。

What you're doing may not be the best way, so perhaps someone can answer with a better approach. But to get your line working you need to make it actually persist the change.

self.price.to_s.gsub(',', '.').to_f

只会返回更改，但不会随处可见

Will just return the change, but that doesn't go anywhere in a callback!

self.price = self.price.to_s.gsub(',', '.').to_f
# OR
self.price.to_s.gsub!(',', '.').to_f

将更改保留在对象中。