ruby-on-rails - ruby on rails 为模型属性更改添加功能

Question

在我的 Rails 模型中，我有一个名为 employer_wcb 的小数属性。如果在更改 employer_wcb 时，脏位设置为 true，我会喜欢它。我想覆盖 employer_wcb setter 方法。有什么方法可以做到这一点(特别是使用元编程)？

Answer 1

所以实际上，从 Rails v2.1 开始，这已经融入到 Rails 中。看看 documentation for ActiveRecord::Dirty .总结:

# Create a new Thing model instance;
# Dirty bit should be unset...
t = Thing.new
t.changed?              # => false
t.employer_wcb_changed? # => false

# Now set the attribute and note the dirty bits.
t.employer_wcb = 0.525
t.changed?              # => true
t.employer_wcb_changed? # => true
t.id_changed?           # => false

# The dirty bit goes away when you save changes.
t.save
t.changed?              # => false
t.employer_wcb_changed? # => false