`cw721-expiration` contract with `invalid NFT` utility

[taitruong]

README.md:

CW721 Expiration

One typical use cases for an cw721-expiration contract is providing services for a limited period, like access cards, SLAs, cloud services, etc. Also check kudos below.

This contract enables the creation of NFTs that expire after a predetermined number of days. The expiration_days is set during instantiation of contract. Expiration timestamp is: mint timestamp + expiration days.

Custom cw721-base Contract

Query Messages

This contract extends cw721-base by adding a new invalid NFT utility. The following cw721-base query messages have been extended with an optional include_invalid property:

• OwnerOf: Queries owner of NFT, by default it throws an invalid NFT error.
• Approval: Queries whether spender has approval for a NFT, by default it throws an invalid NFT error.
• Approvals: Queries all approvals for a NFT, by default it throws an invalid NFT error.
• NftInfo: Queries NFT Info data, by default it throws an invalid NFT error.
• AllNftInfo: Queries NFT Info data, owner, and approvals, by default it throws an invalid NFT error.
• Tokens: Queries all token IDs owned by given address, by default it filters invalid NFTs.
• AllTokens: Queries all token IDs, by default it filters invalid NFTs.

In case NFT is invalid (due to expiration) an error is thrown or filtered out. Above queries for including invalid NFTs must explicitly pass include_invalid: Some(true) (in all other cases (None, Some(false)) invalid NFTs are excluded).

Execute Messages

Execute messages are kept unchanged, but during execution an error is thrown for invalid NFTs for these operations:

• TransferNft: Transfers a NFT to another account without triggering an action.
• SendNft: Sends a NFT to another account and triggering an action.
• Approve: Allows operator/spender to transfer, send, and burn an NFT.
• Revoke: Revokes above approval.
• Burn: Burns an NFT.

Instantiation

To instantiate a new instance of this contract you must specify expiration_days - along with cw721-based properties: owner (aka minter), name, and symbol.

[taitruong]

Kudos to timpi for requesting this kind of NFTs, allowing NFT holders running nodes for a limited period.

[taitruong]

Some side notes to be addressed in other tasks. Mainly most of the code was simply copy-pasted from cw721-base. Imo this shows cw721-base is not modular/generic enough for custom c721-contracts. My suggestions:

• adjust cw721 contract
  • create a new template (as noted in #118)
  • provide default implementations for traits (see #135)
  • always pass deps, env, info for query and execute messages - otherwise traits cant be used, instead code needs to be duplicated like in this case.
  • other minor changes and renamings like:

  • 136

  • rename check_can_send -> check_approval, also approval and operator is kinda confusing
• use Sylvia
  • see PR: https://github.com/CosmWasm/cw-nfts/pull/127
  • also check this on Generics support soon: https://github.com/CosmWasm/sylvia/issues/217

Imo, by doing so, building custom, extended cw721 contracts get much faster done and better, with less/no copy paste code.

[taitruong]

@taitruong LGTM! Mind fixing the one linting error?

Done. Also fixes #141