Detailed Instructions

First, explicitly define the fungibility requirements of your assets. ERC-721 is mandatory for unique, non-fungible assets like individual high-value artwork. ERC-1155 is suitable for semi-fungible items like in-game potions or event tickets where multiple identical copies exist. Next, evaluate the need for batch operations. If your application involves frequent airdrops, marketplace listings, or transfers of multiple tokens to reduce gas costs, ERC-1155's native safeBatchTransferFrom is a critical advantage. Finally, consider metadata complexity. ERC-721 typically uses a single tokenURI per token, while ERC-1155 can use a single URI for an entire token type, which is more efficient for large collections of identical items.

Tip: For lending protocols, ERC-721's uniqueness simplifies collateral valuation, while ERC-1155's batchability can streamline liquidity provisioning.

Detailed Instructions

Initialize a new Hardhat or Foundry project. Install the OpenZeppelin Contracts library, which provides audited implementations of both standards. For ERC-721, you will import @openzeppelin/contracts/token/ERC721/ERC721.sol. For ERC-1155, import @openzeppelin/contracts/token/ERC1155/ERC1155.sol. If using ERC-1155, also consider the ERC1155Supply extension for tracking total circulating supply per token ID, which is essential for financial logic. Configure your hardhat.config.js or foundry.toml for your target network (e.g., Ethereum Mainnet, Polygon). Set up environment variables for your deployer private key and RPC URLs using a .env file.

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// Example package.json dependency
"dependencies": {
  "@openzeppelin/contracts": "^5.0.0"
}

Tip: Use forge install OpenZeppelin/openzeppelin-contracts for Foundry projects to manage dependencies via git submodules.

Detailed Instructions

Create your contract inheriting from the chosen OpenZeppelin base. For an ERC-721 lending vault, you might extend ERC721 and Ownable. Override the _baseURI() function to point to your metadata service. For ERC-1155, implement the uri(uint256 id) function to return a JSON metadata URI for each token ID. Crucially, add your financial logic hooks. For a rental protocol, you might override _beforeTokenTransfer in ERC-721 to check if the token is currently locked in a rental agreement. In ERC-1155, implement access control using the _isAuthorized check for batch operations. Ensure you handle the receiver contract check by implementing IERC721Receiver or IERC1155Receiver on any contract that will custody tokens.

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// ERC-1155 Contract Skeleton
import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";
contract MyGameItem is ERC1155 {
    constructor() ERC1155("https://api.example/item/{id}.json") {}
    function mintBatch(address to, uint256[] memory ids, uint256[] memory amounts) external {
        _mintBatch(to, ids, amounts, "");
    }
}

Tip: Use the supportsInterface function correctly to declare compliance with your chosen standard and any extensions like metadata or enumerable.

Detailed Instructions

Develop tests using Hardhat/Waffle or Foundry's Solidity test framework. Focus on edge cases specific to NFT-Fi. Test that an ERC-721 loan correctly prevents transfers when collateralized by mocking a lending contract. For ERC-1155, verify batch operations: ensure balanceOfBatch returns correct values and that a batch transfer of 3 different token IDs with amounts [1, 50, 100] succeeds atomically. Write tests for reentrancy attacks on your financial functions. Use fuzzing (e.g., Foundry's forge test --fuzz-runs 1000) to test with random inputs. Check that the safeTransferFrom function correctly reverts when sending to a non-receiver contract. Measure gas costs for key operations like minting 10 items (ERC-721 requires 10 txns, ERC-1155 requires 1) to validate your efficiency assumptions.

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// Foundry test example for ERC-1155 batch safety
function testBatchTransferRevertsOnNonReceiver() public {
    address nonReceiver = address(0x123);
    uint256[] memory ids = new uint256[](1);
    uint256[] memory amounts = new uint256[](1);
    ids[0] = 1; amounts[0] = 1;
    vm.expectRevert();
    myERC1155.safeBatchTransferFrom(address(this), nonReceiver, ids, amounts, "");
}

Tip: Integrate static analysis tools like Slither or Mythril into your CI pipeline to catch common vulnerabilities early.

Detailed Instructions

Write a deployment script using Hardhat's deploy or a Foundry script. Deploy to a testnet like Sepolia or Goerli first. For ERC-721, you may need to deploy a separate metadata renderer contract or configure a centralized URI. For ERC-1155, ensure your URI server (e.g., IPFS or Arweave) is live and returns valid JSON metadata for the {id} placeholder. After deployment, immediately verify the contract source code on Etherscan or Blockscout using the relevant plugin (hardhat-etherscan). This is crucial for user trust. Then, perform on-chain integration tests: use a script to mint tokens, call your financial functions (e.g., list for sale on a test marketplace), and execute transfers. Confirm events like TransferSingle (ERC-1155) or Transfer (ERC-721) are emitted correctly.

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# Example Hardhat verify command
npx hardhat verify --network sepolia DEPLOYED_CONTRACT_ADDRESS "ConstructorArg1" "https://ipfs.io/ipfs/QmX.../{id}.json"

Tip: Use a defender or OpenZeppelin Relayer for secure, managed private key signing during deployment to mainnet.

Detailed Instructions

In your front-end (e.g., using ethers.js or viem), instantiate the contract using the ABI and deployed address. Key differences arise in wallet interaction. For ERC-721, use contract.safeTransferFrom(from, to, tokenId). For ERC-1155, use contract.safeBatchTransferFrom(from, to, ids, amounts, data). Implement approval handling: ERC-721 uses setApprovalForAll(operator, true/false) or approve(spender, tokenId), while ERC-1155 primarily uses setApprovalForAll. To display user balances, call balanceOf (ERC-721) or balanceOfBatch (ERC-1155). Set up an indexing service like The Graph or use an Alchemy NFT API webhook. For ERC-1155, your subgraph must handle the TransferBatch event and parse the arrays of IDs and amounts. Ensure your UI correctly displays fungible vs. non-fungible token types from the same contract.

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// viem example for reading ERC-1155 batch balance
const [balance1, balance2] = await publicClient.readContract({
  address: contractAddress,
  abi: erc1155ABI,
  functionName: 'balanceOfBatch',
  args: [[user1, user1], [tokenId1, tokenId2]]
});

Tip: For marketplaces, ensure your integration checks isApprovedForAll before attempting to list items for sale to prevent failed transactions.