test is a specific field is modified

Hey Martin,

There are a couple ways you can do this. The first is to write a
custom setter method for the boolean value:

class Foo < ActiveRecord::Base
  def bool_field=(b)
    self.date_field = Time.now
    write_attribute :bool_field, b

The other way is to use an Observer.

class FooObserver < ActiveRecord::Observer
  def before_update(foo)
    old_foo = Foo.find foo.id
    foo.date_field = Time.now if foo.bool_field != old_foo.bool_field

or you could put it directly in the Foo class...

class Foo < ActiveRecord::Base
  before_update :update_time

  def update_time
    old_foo = Foo.find id
    self.date_field = Time.now if self.bool_field != old_foo.bool_field

Now that I've written them all out, I think the last solution would be
best :slight_smile: I would use the middle solution if I had lots of stuff to do
when a record was modified.


I *think* you would have to add a
return true

at the end of that method, because otherwise Rails will think that
some validation failed and it won't save the record. I'm not 100%
sure though.