Alchemy Core Workflow B — NFT & Smart Contract Interaction

Overview

Build NFT collection explorers and smart contract read operations using Alchemy's NFT API and core JSON-RPC methods.

Prerequisites

• Completed alchemy-install-auth setup
• Familiarity with alchemy-core-workflow-a
• Understanding of ERC-721 and ERC-1155 standards

Instructions

Step 1: NFT Collection Explorer

// src/nft/collection-explorer.ts
import { Alchemy, Network } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function exploreCollection(contractAddress: string) {
  const metadata = await alchemy.nft.getContractMetadata(contractAddress);

  return {
    address: contractAddress,
    name: metadata.name || 'Unknown',
    symbol: metadata.symbol || '',
    totalSupply: metadata.totalSupply || '0',
    tokenType: metadata.tokenType,
    floorPrice: metadata.openSeaMetadata?.floorPrice || null,
    description: metadata.openSeaMetadata?.description || '',
    imageUrl: metadata.openSeaMetadata?.imageUrl || null,
  };
}

async function getCollectionNfts(contractAddress: string, limit: number = 20) {
  const response = await alchemy.nft.getNftsForContract(contractAddress, { limit });
  return response.nfts.map(nft => ({
    tokenId: nft.tokenId,
    name: nft.name || `#${nft.tokenId}`,
    description: nft.description,
    image: nft.image?.cachedUrl || nft.image?.originalUrl,
    attributes: nft.raw?.metadata?.attributes || [],
  }));
}

// Example: Bored Ape Yacht Club
const BAYC = '0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D';
exploreCollection(BAYC).then(console.log).catch(console.error);

Step 2: Batch NFT Metadata

// src/nft/batch-metadata.ts
import { Alchemy, Network } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function batchGetNftMetadata(
  tokens: Array<{ contractAddress: string; tokenId: string }>
) {
  const results = await alchemy.nft.getNftMetadataBatch(
    tokens.map(t => ({ contractAddress: t.contractAddress, tokenId: t.tokenId }))
  );
  return results.map(nft => ({
    contract: nft.contract.address,
    tokenId: nft.tokenId,
    name: nft.name,
    image: nft.image?.cachedUrl,
    tokenType: nft.tokenType,
    collection: nft.contract.name,
  }));
}

Step 3: Smart Contract Read via Ethers + Alchemy Provider

// src/contracts/read-contract.ts
import { Alchemy, Network } from 'alchemy-sdk';
import { ethers } from 'ethers';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function readErc20Contract(contractAddress: string) {
  const provider = await alchemy.config.getProvider();
  const erc20Abi = [
    'function name() view returns (string)',
    'function symbol() view returns (string)',
    'function decimals() view returns (uint8)',
    'function totalSupply() view returns (uint256)',
    'function balanceOf(address) view returns (uint256)',
  ];

  const contract = new ethers.Contract(contractAddress, erc20Abi, provider);
  const [name, symbol, decimals, totalSupply] = await Promise.all([
    contract.name(), contract.symbol(), contract.decimals(), contract.totalSupply(),
  ]);

  return { address: contractAddress, name, symbol, decimals, totalSupply: ethers.formatUnits(totalSupply, decimals) };
}

// Example: Read USDC contract
readErc20Contract('0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48').then(console.log);

Step 4: NFT Ownership Verification

// src/nft/verify-ownership.ts
import { Alchemy, Network } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function verifyNftOwnership(
  ownerAddress: string,
  contractAddress: string,
  tokenId?: string,
): Promise<boolean> {
  if (tokenId) {
    const owners = await alchemy.nft.getOwnersForNft(contractAddress, tokenId);
    return owners.owners.some(o => o.toLowerCase() === ownerAddress.toLowerCase());
  }
  const nfts = await alchemy.nft.getNftsForOwner(ownerAddress, {
    contractAddresses: [contractAddress],
  });
  return nfts.totalCount > 0;
}

Output

• NFT collection explorer with OpenSea metadata and floor price
• Batch metadata fetching for gallery views
• Smart contract read operations via Ethers.js provider
• NFT ownership verification for token-gating

Examples

Use a known public testnet collection or a contract you control to fetch a small page of metadata, then render the collection address, token IDs, and cached-image fallback without treating metadata as verified financial or ownership advice. For token gating, call verifyNftOwnership only after the user has proved control of the wallet through your application’s own signed challenge; an address submitted in a form is not authentication. If an RPC call reverts, metadata is absent, or image retrieval times out, preserve the valid fields, label the unavailable item, and retry only within the configured rate-limit budget.

Error Handling

Error	Cause	Solution
Contract not found	Wrong address or chain	Verify contract on correct network
call revert exception	ABI mismatch	Verify contract implements the interface
Rate limit on batch	Too many requests	Reduce batch size; add delay
Empty NFT images	IPFS timeout	Use Alchemy's cachedUrl field

Resources

• Alchemy NFT API
• Alchemy SDK GitHub
• Ethers.js v6

Next Steps

For common errors and debugging, see alchemy-common-errors.