# 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](/developers/ddo-specification.md) to know more about additional the fields which can be updated.

#### Prerequisites

* [Obtain an API key](/developers/get-api-keys-for-blockchain-access.md)
* [Set up the .env file](/developers/ocean.js/configuration.md#create-a-env-file)
* [Install the dependencies](/developers/ocean.js/configuration.md#setup-dependencies)
* [Create a configuration file](/developers/ocean.js/configuration.md#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.js`) and `.env` files are present, and copy the code as listed below.

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

```javascript
// Note: Make sure .env file and config.js are created and setup correctly
const { oceanConfig } = require('./config.js');
const { ZERO_ADDRESS, NftFactory, getHash, Nft } = require ('@oceanprotocol/lib');

// 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 publisherAccount = await oceanConfig.publisherAccount.getAddress();
  
  // Fetch ddo from Aquarius
  const ddo = await await oceanConfig.aquarius.resolve(did);

  const nft = new Nft(config.publisherAccount);

  // 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"];

  const providerResponse = await oceanConfig.ethersProvider.encrypt(ddo, process.env.OCEAN_NETWORK_URL);
  const encryptedResponse = await providerResponse;
  const metadataHash = getHash(JSON.stringify(ddo));

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

  // Check if ddo is correctly udpated in Aquarius 
  await oceanConfig.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

```bash
node updateMetadata.js
```

{% endtab %}
{% endtabs %}

We provided several code examples using the Ocean.js library for interacting with the Ocean Protocol. Some highlights from the [code examples](https://github.com/oceanprotocol/ocean.js/blob/main/CodeExamples.md) ([compute examples](https://github.com/oceanprotocol/ocean.js/blob/main/ComputeExamples.md)) are:

1. **Minting an NFT** - This example demonstrates how to mint an NFT (Non-Fungible Token) using the Ocean.js library. It shows the necessary steps, including creating a NFTFactory instance, defining NFT parameters, and calling the `create()` method to mint the NFT.
2. **Publishing a dataset** - This example explains how to publish a dataset on the Ocean Protocol network. It covers steps such as creating a DDO, signing the DDO, and publish the dataset.
3. **Consuming a dataset** - This example demonstrates how to consume a published dataset. It shows how to search for available assets, retrieve the DDO for a specific asset, order the asset using a specific datatoken, and then download the asset.

You can explore more detailed code examples and explanations on Ocean.js [readme](https://github.com/oceanprotocol/ocean.js#readme).


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.oceanprotocol.com/developers/ocean.js/update-metadata.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.