Deploy an NFT to Asset Hub¶

Introduction¶

Non-Fungible Tokens (NFTs) represent unique digital assets commonly used for digital art, collectibles, gaming, and identity verification. Asset Hub supports EVM-compatible smart contracts through PolkaVM, enabling straightforward NFT deployment.

This tutorial guides you through deploying an ERC-721 NFT contract on the Westend TestNet using the Polkadot Remix IDE, a web-based development environment. To ensure security and standard compliance, it uses OpenZeppelin's NFT contracts implementation.

Prerequisites¶

Before starting, make sure you have:

MetaMask installed and connected to Westend Asset Hub, check the Connect to Asset Hub guide for more information
A funded account with some WND tokens (you can get them from the Westend Faucet, noting that the faucet imposes a daily token limit, which may require multiple requests to obtain sufficient funds for testing)
Basic understanding of Solidity and NFTs, see the Solidity Basics and the NFT Overview guides for more details

Create the NFT Contract¶

To create the NFT contract, you can follow the steps below:

Navigate to the Polkadot Remix IDE
Click in the Create new file button under the contracts folder, and name your contract as MyNFT.sol
Now, paste the following NFT contract code into the editor
MyNFT.sol
```
// SPDX-License-Identifier: MIT
// Compatible with OpenZeppelin Contracts ^5.0.0
pragma solidity ^0.8.22;

import {ERC721} from "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

contract MyToken is ERC721, Ownable {
    uint256 private _nextTokenId;

    constructor(address initialOwner)
        ERC721("MyToken", "MTK")
        Ownable(initialOwner)
    {}

    function safeMint(address to) public onlyOwner {
        uint256 tokenId = _nextTokenId++;
        _safeMint(to, tokenId);
    }
}
```
The key components of the code above are:
- Contract imports
  - ERC721.sol - the base contract for non-fungible tokens, implementing core NFT functionality like transfers and approvals
  - Ownable.sol - provides basic authorization control, ensuring only the contract owner can mint new tokens
- Constructor parameters
  - initialOwner - sets the address that will have administrative rights over the contract
  - "MyToken" - the full name of your NFT collection
  - "MTK" - the symbol representing your token in wallets and marketplaces
- Key functions
  - _safeMint(to, tokenId) - an internal function from ERC721 that safely mints new tokens. It includes checks to ensure the recipient can handle ERC721 tokens, with the _nextTokenId mechanism automatically generating unique sequential token IDs and the onlyOwner modifier restricting minting rights to the contract owner
  - Inherited Standard ERC721 functions provide a standardized set of methods that enable interoperability across different platforms, wallets, and marketplaces, ensuring that your NFT can be easily transferred, traded, and managed by any system that supports the ERC721 standard:
    - transferFrom(address from, address to, uint256 tokenId) - transfers a specific NFT from one address to another
    - safeTransferFrom(address from, address to, uint256 tokenId) - safely transfers an NFT, including additional checks to prevent loss
    - approve(address to, uint256 tokenId) - grants permission for another address to transfer a specific NFT
    - setApprovalForAll(address operator, bool approved) - allows an address to manage all of the owner's NFTs
    - balanceOf(address owner) - returns the number of NFTs owned by a specific address
    - ownerOf(uint256 tokenId) - returns the current owner of a specific NFT
Tip

Use the OpenZeppelin Contracts Wizard to generate customized smart contracts quickly. Simply configure your contract, copy the generated code, and paste it into Polkadot Remix IDE for deployment. Below is an example of an ERC-721 token contract created with it:

Compile the Contract¶

Compilation is a stage that converts your Solidity source code into bytecode suitable for deployment on the blockchain. Throughout this process, the compiler examines your contract for syntax errors, verifies type safety, and produces machine-readable instructions for execution on the blockchain.

Select the Solidity Compiler plugin from the left panel
Click in the Compile MyNFT.sol button
If the compilation succeeded, you can see a green checkmark indicating success in the Solidity Compiler icon

Deploy the Contract¶

Deployment is the process of uploading your compiled smart contract to the blockchain, allowing for interaction. During deployment, you will instantiate your contract on the blockchain, which involves:

Select the Deploy & Run Transactions plugin from the left panel
Configure the deployment settings
1. From the ENVIRONMENT dropdown, select Westend Testnet - MetaMask
2. From the ACCOUNT dropdown, select the account you want to use for the deploy
Configure the contract parameters
1. Enter the address that will own the deployed NFT.
2. Click the Deploy button to initiate the deployment
MetaMask will pop up - review the transaction details. Click Confirm to deploy your contract

Deploying this contract requires paying gas fees in WND tokens on the Westend Asset Hub TestNet. Ensure your MetaMask account is funded with sufficient WND tokens from the Westend Faucet before confirming the transaction, check the Test Tokens section for more information. Gas fees cover the computational resources needed to deploy and execute the smart contract on the blockchain.

If the deployment process succeeded, you will see the following output in the terminal:

Interact with Your NFT Contract¶

Once deployed, you can interact with your contract through Remix:

Find your contract under Deployed/Unpinned Contracts, and click it to expand the available methods for the contract
To mint an NFT
1. Click on the contract to expand its associated methods
2. Expand the safeMint function
3. Enter the recipient address
4. Click Transact
Click Confirm to confirm the transaction in MetaMask

If the transaction is successful, the terminal will display the following output, which details the information about the transaction, including the transaction hash, the block number, the associated logs, and so on.

Feel free to explore and interact with the contract's other functions using the same approach - selecting the method, providing any required parameters, and confirming the transaction through MetaMask when needed.

Last update: April 9, 2025
| Created: April 9, 2025