Mongoid embedded documents not maintaining reference?

Question

So this behavior is counter to what I would have expected. Let's say I have a document that has 1-n embedded images (well, the metadata for the images). I notice that if I do this:

doc.images.first.alt = 'some alt text'
doc.save

everything works as normal. If I first get a ref to the image:

i = doc.images.first
i.alt = 'some alt text'
doc.save # and/or i.save

The alt text is not saved. Is that the expected behavior?

Answer 1

Assigning docs.images.first to a var means you are changing that variable, not the originating object.

Think of it like a nested hash

a = { x: 1, y: { z: 3 }}

If you set:

b = a[:y]

Changing stuff in b does not affect a.