problem with combined use of touch and autosave options

This behavior seems correct - calling the user.memberships touches the group (updating one of it's attributes) and then the autosave falls back down through the associations to find that the group has been changed, thus updating it's attribute.

Nothing wrong here.

Jamie I am not sure I understand what you wrote.

From what I see in my console sequence, calling "user.memberships" does not touch the group, it just loads the membership associated to the user. When I save the user, the membership is not updated in the DB as it has not changed itself. As the membership record does not change in the database, I don't understand why the group is updated in the database.

Sounds like a bug for me.

I've looked in ActiveRecord code and now I think I understand what you mean Jamie.

:autosave option calls the save method of the loaded association records. In my case the association (membership) has not changed so when its save method is called, the DB record is not changed.

But calling this save method is enough for the touch mechanism to occur, that's why the group is updated in the database. This is because touch is implemented as a after_save callback.

I could "fix" my problem by changing the autosave code so that it calls the association save method only if the association itself has changed. In activerecord-2.3.3/lib/active_record, method save_collection_association I changed the last condition

elsif autosave
  record.save(false)
end

elsif autosave && record.changed?
  record.save(false)
end







I am not familiar with Rails internals and structure, so before going further and submitting a patch with tests, I would like to know if it the right way to fix this issue. Any indication would appreciated :)

only saving the record when it changed seems fine with me and should be done even if it would work with your touch example.
if somebody needs to save all associated records every time for what ever he might need touch for has_many.

i thought of a case where people validate the association record with stuff from the parent, say association.name must be present if parent is in state open or something like this. but that wouldnt be affected cause validations would still be done.

so +1 from me for adding "&& record.changed?"

Thanks!