How to send already minted NFT using alchemy

Question

I have minted some NFTs on opensea. These are on Polygon Mumbai network. Now I want to transfer these to token to other addresses using alchemy web3. Here is the code I am using.

Note: This is supposed to run in nodejs restful API, so there is no wallet available that why I am manually signing the transaction.

async function main() {
  require('dotenv').config();
  const { API_URL,API_URL_TEST, PRIVATE_KEY } = process.env;
  const { createAlchemyWeb3 } = require("@alch/alchemy-web3");
  const web3 = createAlchemyWeb3(API_URL_TEST);
  const myAddress = '*************************'
  const nonce = await web3.eth.getTransactionCount(myAddress, 'latest');
  const transaction = { //I believe transaction object is not correct, and I dont know what to put here
      'asset': {
        'tokenId': '******************************',//NFT token id in opensea
      },
      'gas': 53000,
      'to': '***********************', //metamask address of the user which I want to send the NFT
      'quantity': 1,
      'nonce': nonce,

    }
 
  const signedTx = await web3.eth.accounts.signTransaction(transaction, PRIVATE_KEY);
  web3.eth.sendSignedTransaction(signedTx.rawTransaction, function(error, hash) {
  if (!error) {
    console.log(" The hash of your transaction is: ", hash, "\n Check Alchemy's Mempool to view the status of your transaction!");
  } else {
    console.log("❗Something went wrong while submitting your transaction:", error)
  }
 });
}
main();

Answer 1

Assumed that you have Metamask installed in your browser, and that the NFT smart contract follows ERC721 Standard

const { API_URL,API_URL_TEST, PRIVATE_KEY } = process.env;
const { createAlchemyWeb3 } = require("@alch/alchemy-web3");
const {abi} = YOUR_CONTRACT_ABI

const contract_address = CONTRACT ADDRESS
require('dotenv').config();


async function main() {
  const web3 = createAlchemyWeb3(API_URL_TEST);  
 web3.eth.getAccounts().then(accounts => {
    const account = account[0]
    const nameContract = web3.eth.Contract(abi, contract_address);
    nameContract.methods.transfer(account, ADDRESS_OF_WALLET_YOU_WANT_TO_SEND_TO, TOKEN_ID).send();
 })
.catch(e => console.log(e));
}
main();

Answer 2

Had the same problem, because there is no example on transferring NFT token. There is a well explained 3-parts-example on ethereum website to mint an NFT.

In the first part, step 10, it explains how to write a contract and also mentions the existing methods in the contract object extended:

After our import statements, we have our custom NFT smart contract, which is surprisingly short — it only contains a counter, a constructor, and single function! This is thanks to our inherited OpenZeppelin contracts, which implement most of the methods we need to create an NFT, such as ownerOf which returns the owner of the NFT, and transferFrom, which transfers ownership of the NFT from one account to another.

So, with these informations, I made an NFT transfer transaction between two addresses with my metamask mobile app. Then I searched the JSON of this transaction through etherscan API.

In this way, I was able to transfer tokens to other addresses using alchemy web3 with this script:

require("dotenv").config()
const API_URL = process.env.API_URL; //the alchemy app url
const PUBLIC_KEY = process.env.PUBLIC_KEY; //my metamask public key
const PRIVATE_KEY = process.env.PRIVATE_KEY;//my metamask private key
const {createAlchemyWeb3} = require("@alch/alchemy-web3")
const web3 = createAlchemyWeb3(API_URL)

const contract = require("../artifacts/contracts/MyNFT.sol/MyNFT.json")//this is the contract created from ethereum example site

const contractAddress = "" // put here the contract address

const nftContract = new web3.eth.Contract(contract.abi, contractAddress)


/**
 * 
 * @param tokenID the token id we want to exchange
 * @param to the metamask address will own the NFT
 * @returns {Promise<void>}
 */
async function exchange(tokenID, to) {
    const nonce = await web3.eth.getTransactionCount(PUBLIC_KEY,         'latest');
//the transaction
const tx = {
    'from': PUBLIC_KEY,
    'to': contractAddress,
    'nonce': nonce,
    'gas': 500000,
    'input': nftContract.methods.safeTransferFrom(PUBLIC_KEY, to, tokenID).encodeABI() //I could use also transferFrom
};
const signPromise = web3.eth.accounts.signTransaction(tx, PRIVATE_KEY)

signPromise

    .then((signedTx) => {

        web3.eth.sendSignedTransaction(
            signedTx.rawTransaction,

            function (err, hash) {

                if (!err) {

                    console.log(
                        "The hash of your transaction is: ",

                        hash,

                        "\nCheck Alchemy's Mempool to view the status of your transaction!"
                    )

                } else {

                    console.log(
                        "Something went wrong when submitting your transaction:",

                        err
                    )

                }

            }
        )

    })

    .catch((err) => {

        console.log(" Promise failed:", err)

    })
}

Answer 3

I Had the same problem. I need to transfer NFT in node.js back-end.
I use network provider to use Moralis NetworkWeb3Connector.

here's my repository for example: https://github.com/HanJaeJoon/Web3API/blob/2e30e89e38b7b1f947f4977a0fe613c882099fbc/views/index.ejs#L259-L275

  await Moralis.start({
    serverUrl,
    appId,
    masterKey,
  });

  await Moralis.enableWeb3({
    // rinkeby
    chainId: 0x4,
    privateKey: process.env.PRIVATE_KEY,
    provider: 'network',
    speedyNodeApiKey: process.env.MORALIS_SPEEDY_NODE_API_KEY,
  });

  const options = {
    type,
    receiver,
    contractAddress,
    tokenId,
    amount: 1,
  };

  try {
    await Moralis.transfer(options);
  } catch (error) {
    console.log(error);
  }

you can get speed node api key in
Moralis dashboad > Networks > Eth Rinkeby(in my case) > Settings

screenshot