Changes to embedded documents not tracked in parent history

[mpetazzoni]

I'm trying to track all changes to a model object and its embedded documents, as described in the "Include embedded objects attributes in parent audit" section of the README.

My models roughly looks like this:

class ParentModel
  include Mongoid::Document
  include Mongoid::Timestamps
  include Mongoid::History::Trackable
  include Mongoid::Userstamp
  mongoid_userstamp user_model: 'User'

  field :foo
  embeds_one :child
  accepts_nested_attributes_for :child

  track_history on: [:fields, :updated_by_id, :embedded_relations],
                modifier_field: :modifier,
                modifier_field_inverse_of: :nil,
                version_field: :version,
                track_create: true,
                track_update: true,
                track_destroy: false
end

class ChildModel
  include Mongoid::Document
  include Mongoid::Timestamps
  include Mongoid::Userstamp
  mongoid_userstamp user_model: 'User'

  field :bar
  embedded_in :parent, inverse_of: :child
end

Changes to fields of the parent are correctly tracked in the parent's history, but not changes to fields of the child.

> p = Parent.all().first
> p.name = "test"
> p.save
> p.history_tracks.reverse.first
### shows the change to the name in the parent document

> p.child.bar = "test"
> p.save
> p.history_tracks.reverse.first
### no additional audit trail entry recorded, this shows the change to the name of the parent from above

Am I misunderstanding how the tracking of embedded relations is supposed to work? Does it only track a change to the reference itself, for example if I change p.child to a completely different child object?

Is there a way for me to accomplish what I'm looking for here, that is to have a single audit trail of parent document that shows all changes to all its fields, and all the fields of its embedded relations?

I was expecting #150 to provide this functionality.

[dblock]

The changes with embedded_relations should have worked.

First I would change save to save! and see whether there're errors. Then I would look at what's actually being written in MongoDB with logger at DEBUG level and make sure it's doing what we think it should be doing.

Finally, try to build a short repro in a spec. One thing that comes to mind - is ChildModel declared after or before?

[mpetazzoni]

I tried with save! as well, no errors. The child object is correctly saved in Mongo, and I can even reload the Parent object (with relations) and get the updated values as expected. It's just the audit trail that's incomplete.

In my application, ParentModel and ChildModel are declared into two distinct files (as you might expect in a Rails app). I don't know in what order those are loaded. From trying to write a spec for it, it does appear that I need to declare the ChildModel before. I'm sending a PR with the spec.

[jagdeepsingh]

@mpetazzoni i tried to replicate the behavior by setting up a minimal example. mongoid-history was not able to catch the changes in embedded documents. It basically works on the parent_object.changes hash and if an embedded object attribute is changed, the changes hash remains empty (that is the default behavior of mongoid). So, no history record is not created in that case (which is a bug in mongoid-history).

There is a gem mongoid_relations_dirty_tracking to see the embedded documents changes in parent object's changes hash. I tried to use that in my example, but it turns out the gem does not support rails 5 and mongoid 6. If you are using a lower version of rails and mongoid, you can give it a try.

Another solution on SO.

It might take some more time to try these solutions on my end. I will let you know if i find a fix. Please let us know, if any of the above solutions work for you.

[bopm]

I have patched for support of Rails5/Mongoid6 mongoid_relations_dirty_tracking here. Problem is that test is still failing even when examples from mongoid_relations_dirty_tracking are fine.

[rubydev]

Any news about it? How you solved it?

[dblock]

#191 seems like it's almost there, but not ready to merge

[rubydev]

How it should work actually? For example in case embeds_many, that parent is Post and children are comments. And one comment was changed, should be in original and modified all comments? Or changed comment only?

Edit: After investigation, I think, that there should be all embedded objects, not changed only.