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Set LSP8 NFT Metadata

In this guide you will learn how to set the metadata of a specific NFT (represented by its bytes32 tokenId) part of a LSP8 Identifiable Digital Asset collection.

Setup​

You will need the address of an existing LSP8 NFT collection in order to follow this tutorial. This represent the LSP8 collection that includes the NFT you want to update metadata for. For instance 0x37934A275EFd47DFce671CA3CBaE34d9138CF2D2.

The following code snippets require the installation of the following libraries:

npm install ethers @lukso/lsp-smart-contracts

Imports and constants​

Import web3.js/ethers, the LSP8IdentifiableDigitalAsset ABI from @lukso/lsp-smart-contracts and create an instance of this contract with the lsp8ContractAddress.

import { ethers } from 'ethers';

// import smart contract ABI
import LSP8IdentifiableDigitalAsset from '@lukso/lsp-smart-contracts/artifacts/LSP8IdentifiableDigitalAsset.json';

const provider = new ethers.BrowserProvider(window.lukso);

await provider.send('eth_requestAccounts', []);

const signer = await provider.getSigner();

const lsp8ContractAddress = '0x...';

Instantiate the LSP8 contract​

Create an instance of the LSP8 collection contract as shown below:

const lsp8Contract = new ethers.Contract(
  lsp8ContractAddress,
  LSP8IdentifiableDigitalAsset.abi,
);

Encode the Metadata​

The next step is to encode the metadata. To do so, we need:

  • a JSON file that contains all the metadata of the specific NFT. This metadata has the same format as the LSP4Metadata.
  • the IPFS url where this JSON file has been uploaded

The value will be encoded as a VerifiableURI. We will use the encodeData function from the erc725.js library to encode a VerifiableURI easily.

encodeVerifiableURI.ts
import { ERC725 } from '@erc725/erc725.js';

import NFTMetadataJSON from './NFTMetadata.json';

const schema = [
  {
    name: 'LSP4Metadata',
    key: '0x9afb95cacc9f95858ec44aa8c3b685511002e30ae54415823f406128b85b238e',
    keyType: 'Singleton',
    valueType: 'bytes',
    valueContent: 'VerifiableURI',
  },
];

const myErc725 = new ERC725(schema);

myErc725.encodeData([
  {
    keyName: 'LSP4Metadata',
    value: {
      json: NFTMetadataJSON,
      url: 'ipfs://QmQTqheBLZFnQUxu5RDs8tA9JtkxfZqMBcmGd9sukXxwRm',
    },
  },
]);

You can also check the code snippet example in the LSP2 specs to learn in details the encoding of a VerifiableURI.

Send the transaction to set metadata for a tokenId​

The last step is to set the metadata for a specific tokenId. You can then send the transaction to set the metadata for the given NFT represented by its tokenId.

Here we will use the following parameters as examples:

  • tokenId: 0x0000000000000000000000000000000000000000000000000000000000000001
  • dataKey: LSP4Metadata
  • metadataValue: some placeholder value as a VerifiableURI.

Note that the tokenId is a bytes32 value (hex)

import { ERC725YDataKeys } from '@lukso/lsp-smart-contracts';

// import and instantiate contract from previous steps

// change this with the actual tokenId to update metadata for
const tokenId =
  '0x0000000000000000000000000000000000000000000000000000000000000001';

// change this with the actual VerifiableURI of the metadata uploaded somewhere (S3, IPFS, etc...)
const metadataValue = '0x...';

await lsp8Contract.setDataForTokenId(
  tokenId,
  ERC725YDataKeys.LSP4['LSP4Metadata'],
  metadataValue,
);