x/nft is an implementation of a Cosmos SDK module, per ADR 43, that allows you to create nft classification, create nft, transfer nft, update nft, and support various queries by integrating the module. It is fully compatible with the ERC721 specification.
x/nft module defines a struct
Class to describe the common characteristics of a class of nft, under this class, you can create a variety of nft, which is equivalent to an erc721 contract for Ethereum. The design is defined in the ADR 043.
The full name of NFT is Non-Fungible Tokens. Because of the irreplaceable nature of NFT, it means that it can be used to represent unique things. The nft implemented by this module is fully compatible with Ethereum ERC721 standard.
Class is mainly composed of
id is the unique identifier of the class, similar to the Ethereum ERC721 contract address, the others are optional.
0x01 | classID | -> ProtocolBuffer(Class)
NFT is mainly composed of
data. Among them,
id are two-tuples that identify the uniqueness of nft,
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
0x02 | classID | 0x00 | nftID |-> ProtocolBuffer(NFT)
NFTOfClassByOwner is mainly to realize the function of querying all nfts using classID and owner, without other redundant functions.
0x03 | owner | 0x00 | classID | 0x00 | nftID |-> 0x01
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.
0x04 | classID | 0x00 | nftID |-> owner
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.
0x05 | classID |-> totalSupply
In this section we describe the processing of messages for the NFT module.
The validation of
NftID is left to the app developer.
The SDK does not provide any validation for these fields.
You can use the
MsgSend message to transfer the ownership of nft. This is a function provided by the
x/nft module. Of course, you can use the
Transfer method to implement your own transfer logic, but you need to pay extra attention to the transfer permissions.
The message handling should fail if:
ClassIDdoes not exist.
Iddoes not exist.
Senderdoes not the owner of nft.
The nft module emits proto events defined in the Protobuf reference.