State

Class

Class is mainly composed of id, name, symbol, description, uri, uri_hash,data where id is the unique identifier of the class, similar to the Ethereum ERC721 contract address, the others are optional.

• Class: 0x01 | classID | -> ProtocolBuffer(Class)

NFT

NFT is mainly composed of class_id, id, uri, uri_hash and data. Among them, class_id and id are two-tuples that identify the uniqueness of nft, uri and uri_hash is optional, which identifies the off-chain storage location of the nft, and data is an Any type. Use Any chain of x/nft modules can be customized by extending this field

• NFT: 0x02 | classID | 0x00 | nftID |-> ProtocolBuffer(NFT)

NFTOfClassByOwner

NFTOfClassByOwner is mainly to realize the function of querying all nfts using classID and owner, without other redundant functions.

• NFTOfClassByOwner: 0x03 | owner | 0x00 | classID | 0x00 | nftID |-> 0x01

Owner

Since there is no extra field in NFT to indicate the owner of nft, an additional key-value pair is used to save the ownership of nft. With the transfer of nft, the key-value pair is updated synchronously.

• OwnerKey: 0x04 | classID | 0x00 | nftID |-> owner

TotalSupply

TotalSupply is responsible for tracking the number of all nfts under a certain class. Mint operation is performed under the changed class, supply increases by one, burn operation, and supply decreases by one.

• OwnerKey: 0x05 | classID |-> totalSupply