Mint NFT (2 of 3)
In this tutorial, we’ll teach you how to do mint an NFT in <10 minutes.
“Minting an NFT” is the act of publishing a unique instance of your FRC-721 token on the blockchain. Using our smart contract from part 1 of this NFT tutorial guide, let’s flex our Web3 skills and mint an NFT. At the end of this tutorial, you’ll be able to mint as many NFTs as your heart (and wallet) desires!
Let’s get started!
Step 1: Install Web3
If you followed the first tutorial on creating your NFT smart contract, you already have experience using Ethers.js. Web3 is similar to Ethers, as it is a library used to make creating requests to the Ethereum-compatible blockchain easier.
To install web3, run
and update mint-nft.js
with the following line
Step 2: Create mint-nft.js File
Inside your scripts directory, create a mint-nft.js
file and add the following lines of code:
Step 3: Grab Contract ABI
Our contract ABI (Application Binary Interface) is the interface to interact with our smart contract. You can learn more about Contract ABIs here. Hardhat automatically generates an ABI for us and saves it in the FindoraNFT.json
file. In order to use this we’ll need to parse out the contents by adding the following lines of code to our mint-nft.js
file:
const contract = require("../artifacts/contracts/FindoraNFT.sol/FindoraNFT.json")
If you want to see the ABI you can print it to your console:
console.log(JSON.stringify(contract.abi))
To run mint-nft.js and see your ABI printed to the console navigate to your terminal and run:
node scripts/mint-nft.js
Step 4: Configure NFT Metadata
If you remember from our tutorial in Part 1, our mintNFT
smart contract function takes in a tokenURI
parameter that should resolve to a JSON document describing the NFT's metadata— which is really what brings the NFT to life, allowing it to have configurable properties, such as a name, description, image, and other attributes.
We will use Pinata, a convenient IPFS API and toolkit, to store our NFT asset and metadata to ensure our NFT is truly decentralized. If you don’t have a Pinata account, sign up for a free account here and complete the steps to verify your email.
Once you’ve created an account:
Navigate to the “Files” page and click the blue "Upload" button at the top-left of the page.
Upload an image to Pinata — this will be the image asset for your NFT. Feel free to name the asset whatever you wish
After you upload, you'll see the file info in the table on the "Files" page. You'll also see a CID column. You can copy the CID by clicking the copy button next to it. You can view your upload at:
https://gateway.pinata.cloud/ipfs/<CID>
.You can find the test image we used on IPFS here -- https://gateway.pinata.cloud/ipfs/QmT5fenaMZ17nBSqBaWyv4PbDV5EZeErRQaDpso5nNBViz.
Now, we’re going to want to upload one more document to Pinata. But before we do that, we need to create it!
In your root directory, make a new file called nft-metadata.json
and add the following json code:
Feel free to change the data in the json. You can remove or add to the attributes section. Most importantly, make sure image field points to the location of your IPFS image — otherwise, your NFT will include a photo of a (very cute!) dog.
Once you’re done editing the JSON file, save it and upload it to Pinata, following the same steps we did for uploading the image.
Step 5: Create Contract Instance
Now, to interact with our contract, we need to create an instance of it in our code. To do so we’ll need our contract address which we can get from the deployment or Etherscan by looking up the address you used to deploy the contract.
In the above example, our contract address is 0x1A6c013c9951d84273176390CeB1Ccfadb45EEce
.
Next, we will use the Web3 contract method to create our contract using the ABI and address. In your mint-nft.js
file, add the following:
Step 6: Update .env File
Now, in order to create and send transactions to the Findora network, we’ll use your public account address to get the account nonce (will explain below).
Add your public key to your .env file and also add the API_URL
that points to Anvil Testnet (i.e. prod-testnet.prod.findora.org:8545").
— if you completed part 1 of the tutorial, our .env
file should now look like this:
Step 7: Create Transaction
First, let’s define a function named mintNFT(tokenData)
and create our transaction by doing the following:
Grab your
PRIVATE_KEY
andPUBLIC_KEY
from the .env file.Next, we’ll need to figure out the account nonce. The nonce specification is used to keep track of the number of transactions sent from your address — which we need for security purposes and to prevent replay attacks. To get the number of transactions sent from your address, we use eth_getTransactionCount.
Finally we’ll set up our transaction with the following info:
'from': PUBLIC_KEY
— The origin of our transaction is our public address'to': contractAddress
— The contract we wish to interact with and send the transaction'nonce': nonce
— The account nonce with the number of transactions sent from our address'gas': estimatedGas
— The estimated gas needed to complete the transaction'data': nftContract.methods.mintNFT(PUBLIC_KEY, md).encodeABI()
— The computation we wish to perform in this transaction — which in this case is minting a NFT.
Your mint-nft.js
file should look like this now:
Step 8: Sign Transaction
Now that we’ve created our transaction, we need to sign it in order to send it off. Here is where we’ll use our private key.
web3.eth.sendSignedTransaction
will give us the transaction hash, which we can use to make sure our transaction was mined and didn't get dropped by the network. You'll notice in the transaction signing section, we've added some error checking so we know if our transaction successfully went through.
Step 9: Call mintNFT and Run Node mint-nft.js
Remember the metadata.json you uploaded to Pinata? Get its hashcode from Pinata and pass the following as parameter to the function mintNFT https://gateway.pinata.cloud/ipfs/<metadata-hash-code>
Here’s how to get the hashcode. Simply copy the value under the CID
column and use that as the <metadata-hash-code>
.
Double check that the hashcode you copied links to your metadata.json by loading https://gateway.pinata.cloud/ipfs/<metadata-hash-code>
into a separate window.
The page should look similar to the screenshot below:
Altogether, your code should look something like this:
Now, run
from your root directory to deploy your NFT. After a couple of seconds, you should see a response like this in your terminal:
Next, visit your Anvil Testnet block explorer to see the status of your transaction (whether it’s pending, mined, or got dropped by the network).
And that’s it! You’ve now deployed AND minted with a NFT on the Findora blockchain 🤑
Using the mint-nft.js
you can mint as many NFT's as your heart (and wallet) desires! Just be sure to pass in a new tokenURI
describing the NFT's metadata (otherwise, you'll just end up making a bunch of identical ones with different IDs).
Presumably, you’d like to be able to show off your NFT in your wallet — so be sure to check out part 3 of this NFT tutorial guide.
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