docs/building-with-ocean/using-ocean-libraries/update-metadata.md

Update Metadata

This tutorial will guide you to update an existing asset published on-chain using Ocean libraries. The tutorial assumes that you already have the did of the asset which needs to be updated. In this tutorial, we will update the name, description, tags of the data NFT. Please refer the page on DDO to know more about additional the fields which can be updated.

Prerequisites

• Obtain an API key
• Set up the .env file
• Install the dependencies
• Create a configuration file

{% hint style="info" %} The variable AQUARIUS_URL and PROVIDER_URL should be set correctly in .env file {% endhint %}

Create a script to update the metadata

Create a new file in the same working directory where configuration file (config.py/config.js) and .env files are present, and copy the code as listed below.

{% tabs %} {% tab title="ocean.js" %} {% code title="updateMetadata.js" %}

// Import dependencies
const {
  Nft,
  ProviderInstance,
  getHash,
  Aquarius
} = require('@oceanprotocol/lib');
const { SHA256 } = require('crypto-js');
const Web3 = require('web3');
const { web3Provider, oceanConfig } = require('./config');

// Create a web3 instance
const web3 = new Web3(web3Provider);

// Create Aquarius instance
const aquarius = new Aquarius(oceanConfig.metadataCacheUri);
const nft = new Nft(web3);
const providerUrl = oceanConfig.providerUri;

// replace the did here
const did = "did:op:a419f07306d71f3357f8df74807d5d12bddd6bcd738eb0b461470c64859d6f0f";

// This function takes did as a parameter and updates the data NFT information
const setMetadata = async (did) => {
  const accounts = await web3.eth.getAccounts();
  const publisherAccount = accounts[0];
  
  // Fetch ddo from Aquarius
  const ddo = await aquarius.resolve(did);

  // update the ddo here
  ddo.metadata.name = "Sample dataset v2";
  ddo.metadata.description = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam";
  ddo.metadata.tags = ["new tag1", "new tag2"];

  providerResponse = await ProviderInstance.encrypt(ddo, providerUrl);
  const encryptedResponse = await providerResponse;
  const metadataHash = getHash(JSON.stringify(ddo));

  // Update the data NFT metadata
  await nft.setMetadata(
    ddo.nftAddress,
    publisherAccount,
    0,
    providerUrl,
    '',
    '0x2',
    encryptedResponse,
    `0x${metadataHash}`
  );

  // Check if ddo is correctly udpated in Aquarius 
  await aquarius.waitForAqua(ddo.id);

  console.log(`Resolved asset did [${ddo.id}]from aquarius.`);
  console.log(`Updated name: [${ddo.metadata.name}].`);
  console.log(`Updated description: [${ddo.metadata.description}].`);
  console.log(`Updated tags: [${ddo.metadata.tags}].`);

};

// Call setMetadata(...) function defined above
setMetadata(did).then(() => {
  process.exit();
}).catch((err) => {
  console.error(err);
  process.exit(1);
});

{% endcode %}

Execute the script

node updateMetadata.js

{% endtab %} {% endtabs %}