Added previous_changes to ActiveRecord::Dirty [PATCH]

Reformatted the example, sorry about that

person = Person.find_by_name('bob')
person.name = 'robert'
person.changes # => {'name' => ['bob, 'robert']}
person.save
person.changes # => {}
person.previous_changes # => {'name' => ['bob, 'robert']} person.reload
person.previous_changes # => {}

Thank goodness for this! Having the dirty changes blown out after save severely limits the usefulness of the dirty state -- this seems like a good compromise.

This patch doesn't apply cleaning for me. I like the idea though.

This patch says the following when applied with git am :

/home/path/rails/.git/rebase-apply/patch:84: trailing whitespace.
    
error: activerecord/lib/active_record/dirty.rb: does not exist in index

inspecting these lines it doesn't appear that there is whitespace however.

The concept is a good idea. Shouldn't you be more worried about what is saving in the before_save callback, vs. what was saved after? Just to play devil's advocate.

I'll clean up the patch and resubmit.

+1

Verified.

Added a few extra tests.

I've attached a patch.

The patch does not apply cleanly to edge since activerecord/lib/active_record/dirty.rb has been moved.

• 1. This seems a bit overboard to me. Using model.#{attribute}_was has always been enough for me, if you're changing it more than once that sounds like bad logic instead to me. I'd like to see some real use cases of this first.

+1, I could see this making the dirty a lot more useful.

A use case I would use this for goes something like:
- I have a Debate that has 'state' attribute for the current state (ie new, forfeited, etc) - I want to make notifications when this state changes - I could use an after_save callback to kick off a mailer to which includes both the old value and the new value.

Thanks David.

I've attached a patch for edge.

Renamed the previous patch for clarity

Adding Josh as he's looking at this in amo

verified

This may be useful, but at least part of your description is misleading - the changed? and was methods work fine inside after_save, as they aren't reset until after the transaction commits.

Lets put it in 3.0.

Can you please rebase against master. I'm about to make some changes to AR dirty tracking in the next few days. I'm extracting them out to AMo.

The original patch wouldn't apply because dirty.rb moved after I submitted the patch.

Let me know what this ticket needs and I'll put it together.