When will ActiveRecord save associations?

Question

1. I know that it will save associations when autosave: true as per https://api.rubyonrails.org/classes/ActiveRecord/AutosaveAssociation.html

Answer 1

Not sure if this will help anyone else, but I recently ran into a similar issue recently in Rails 5.2.

When trying to save an object 2 layers deep my tests failed if the top level and the first level objects had already been saved. Ie.

book_cover.persisted? == true
book_cover.book.persisted? == true

page = book_cover.book.pages.new

page.persisted? == false

# After saving the top level object
book_cover.save
page.persisted? == false

# After saving the immediate parent of page
book_cover.book.save
page.persisted? == true

Since the parent "book cover" wasn't the direct parent of the new object "page" saving "book cover" didn't actually end up saving the "page" object.

Depending on the situation I just explicitly called save on the "book" object to save all the child objects.