Re-creating deleted stock items

[steveh]

Disclaimer: I'm not sure if this is a bug or I've misunderstood how this should work.

If I have a StockItem for a Variant and StockLocation, and I delete that StockItem, it remains in the database, due to acts_as_paranoid.

However, I can't re-create it, due to a uniqueness constraint:
validates_uniqueness_of :variant_id, scope: :stock_location_id.

I see TaxCategory adds deleted_at to the scope, i.e.
validates_uniqueness_of :variant_id, scope: [:stock_location_id, :deleted_at] ?

But I'm not sure that's right either, as undeleted stock items will have a NULL deleted_at, and NULL != NULL in SQL, so that uniqueness constraint will allow multiple undeleted products.

Steps to reproduce:

1. Add some stock to a variant in a given location
2. Delete that stock
3. Try and add some to stock to the same variant and the same location
4. ActiveRecord::RecordInvalid (Validation failed: Variant has already been taken)

Expected behaviour:

• Able to add new stock without regard to stock that has been previously deleted

Versions:

• Spree 2.1.1
• Rails 4.0.0

Gemfile and stack trace: https://gist.github.com/steveh/6862586

I've added this (horrible) workaround for the time being:

module Spree
  StockItem.class_eval do
    _validators.reject!{ |key, _| key == :variant_id }

    _validate_callbacks.reject! do |callback|
      callback.raw_filter.try(:attributes) == [:variant_id]
    end

    validates_uniqueness_of :variant_id, scope: [:stock_location_id, :deleted_at]
  end
end

[huoxito]

Hi @steveh it seems to me your suggestion works just fine. Could you please update and confirm thats fixed? thanks for reporting.