Consider dropping `nft-sales` in favour of `pallet_uniques`

[NunoAlexandre]

Motivation

Since this PR, the pallet_uniques offers a set_price and a buy_item extrinsics to allow for NFT owners to set their NFTs up for sale for a given asking price and for potential buyers to buy said NFTs for said price. This functionality is exactly what we handcrafted with nft-sales.

Proposal / Consideration

Since nft-sales is essentially just duplicated logic, we can choose to adopt the official pallet_uniques API instead.

Pros

• Less code to maintain
• One less pallet in our runtime
• Following community standards
• Simpler solution since users don't need to give up ownership of their NFTs to the nft-sales pallet to sell their NFTs

Migration requirements

• The frontend would need to switch to pulling NFTs for sale from the pallet_uniques
• migration: active NFTs for sale on nft-sales would need to be removed and their ownership restored to the original owner

Questions

• How many active NFTs for sale on nft-sales do we have in Kusama?

[NunoAlexandre]

@onnovisser it would be cool getting your thoughts on this regarding potential work that would need to happen in the frontend that we may not be considering now.

[onnovisser]

The surface area of NFT sales is pretty small, so shouldn't need much rework. Is there an extrinsic to remove an nft from being listed?

[NunoAlexandre]

The surface area of NFT sales is pretty small, so shouldn't need much rework. Is there an extrinsic to remove an nft from being listed?

Well, we have a remove extrinsic but that would require every user with NFTs up for sale to call that extrinsic. An alternative would be for us to write a migration script that would basically do that automatically on_runtime_upgrade.

So we could have that and have the UI switch to adopt the pallet_uniques API. Users who had NFTs open for sale would need to call basically putting them up for sale again, which would then happen through pallet_uniques.

Wdyt?

[onnovisser]

That sounds good to me. With my question, I meant to ask if the new pallet_uniques has an extrinsic to remove an item from sale, as users will need to still be able to do that in the new version, and it only mentions set_price and buy_item. Looking at the code though, it looks like I can call set_price with None to remove an item from sale.

[jsidorenko]

Yes, you can remove the price by setting it to None. Btw, feel free to consider waiting a bit and switching to the new "uniques-v2" pallet that would bring much more features and control over nfts

[NunoAlexandre]

Thanks for chipping in, @jsidorenko. @onnovisser let's wait for Uniques v2 then 👍