Cannot add backorderable products to cart in admin

[mdamian322]

Steps to reproduce

1. Have a product that has 0 stock but is backorderable
2. Create a new order in admin
3. On the cart tab, search for that product in order to add it to the cart
4. No results come up

Expected behavior
I expect the product to come up in search so I can add it to the customer's cart since it's backorderable. On the frontend, the customer is able to purchase it just fine.

Actual behavior
The product does not show up and I am not able to add it to the cart.

System configuration
2.4

[jhawthorn]

Can confirm this issue. The problem is that most of our admin variant selectors use in_stock_only: true. Our terminology in the API and core is that in_stock means essentially count_on_hand > 0 || !track_inventory?.

We should introduce a new scope to mean any variant which we could put in an order: count_on_hand > 0 || backordered? || !track_inventory?.

I have no idea what to call this scope. Any suggestions?

can_supply? is probably the nearest match. So maybe something named similarly to that?

[skukx]

I like the idea of can_supply? or close to that (can_dispurse?, can_fulfill?, can_allocate?) and the name makes sense for the functionality it will provide. Items that are in stock, or backorderable, or don't require tracking. Possibly add a scope to the variant called suppliable to go with the in_stock scope.

Spree::Variant.in_stock
Spree::Variant.suppliable

See: https://github.com/solidusio/solidus/blob/master/api/app/controllers/spree/api/variants_controller.rb#L70

[jhawthorn]

I believe this is fixed by #2536