Sometimes it’s nice to be able to access a version of an ActiveRecord object before certain changes are applied, e.g.:
class Foo < ActiveRecord::Base
def foobar
some_attribute
end
around_update :bar
def bar
pp self.foobar # At this point, I'd like to be able to inspect the 'old' state
yield
pp self.foobar
end
end
Currently, ActiveRecord::Dirty provides some methods to inspect changes and older values of specific attributes through changes and *_was, but not the entire previous state. Having access to it would allow you to call instance methods using the old state.
I propose to add the following instance method to ActiveRecord::Dirty:
def self_was
self.changes.each_with_object(self.dup) {|(attribute,(previous_value,_)), object|
object.write_attribute(attribute, previous_value)
}
end
So we can replace self by self_was before the yield and get the behavior that we want.
Heads up: I will probably not look back at this topic, as I’ve already opted to use this feature in my own repo. This is just my two cents on a missing feature in ActiveRecord::Dirty. Initially posted it as an issue (Inspecting old state of ActiveRecord object "before `changes`" · Issue #48243 · rails/rails · GitHub), but got redirected here.
