Clone user addresses instead of sharing

[fkoessler]

Order#bill_address and Order#ship_address use the
dependent: :destroy option. We should not share
user addresses with orders or the user addresses might
be deleted. OrderMerger destroys orders for example.

[viezly]

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[damianlegawiec]

@fkoessler this was the case before the address book was merged into spree core.

The end result was that in bigger stores the addresses table could grow to up 50+ million records. It was unmanageable.

Currently, you cannot delete an address that belongs to completed orders.

[fkoessler]

Hello @damianlegawiec , thank you for your feedback.
I understand the problem with duplicating all addresses.

I noticed the issue because one of my user had bill_address_id / ship_address_id that link to deleted addresses after OrderMerger deleted an incomplete Order: https://github.com/spree/spree/blob/main/core/app/models/spree/order_merger.rb#L23
This is an problem too.

Also, I noticed that addresses were cloned in other places in the Spree code base:

• https://github.com/spree/spree/blob/main/core/app/models/concerns/spree/user_methods.rb#L88
• https://github.com/spree/spree/blob/main/core/app/models/spree/order.rb#L296

It's a bit confusing, I could not find out if Spree expects addresses to be shared or cloned.
I think a single strategy should be used throughout the codebase.

What do you think?

[fkoessler]

Related to: #11682