Add code from erc721 101 class (#5)

erc721-solidity-101/.env_sample

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+API_URL = "https://eth-rinkeby.alchemyapi.io/v2/<project>"
+PUBLIC_KEY = 
+PRIVATE_KEY = 
+METADATA_URL = <pinata IPFS cid dor metadata>"
+CONTRACT_ADDRESS = 

erc721-solidity-101/README.md

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+# One: A special summer
+
+
+1. Compile contract:
+
+```
+npx hardhat compile
+```
+
+2. Deploy contract:
+
+```
+npx hardhat run scripts/deploy-contract.js --network rinkeby
+```
+
+3.  Mint NFT:
+
+```
+node scripts/mint-nft.js
+```

erc721-solidity-101/contracts/MiaNFT.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity >=0.7.3 <0.9.0;
+
+import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
+import "@openzeppelin/contracts/utils/Counters.sol";
+import "@openzeppelin/contracts/access/Ownable.sol";
+
+
+contract MiaNFT is ERC721, Ownable {
+
+    using Counters for Counters.Counter;
+    Counters.Counter private _tokenIds;
+
+    constructor() public ERC721("Mia's NFT, "NFT") {}
+
+    function mintNFT(address recipient, string memory tokenURI)
+        public onlyOwner
+        returns (uint256)
+    {
+        _tokenIds.increment();
+
+        uint256 newItemId = _tokenIds.current();
+        _mint(recipient, newItemId);
+        _setTokenURI(newItemId, tokenURI);
+
+        return newItemId;
+    }
+}

erc721-solidity-101/hardhat.config.js

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+/**
+* @type import('hardhat/config').HardhatUserConfig
+*/
+require('dotenv').config();
+require("@nomiclabs/hardhat-ethers");
+
+const { API_URL, PRIVATE_KEY } = process.env;
+
+module.exports = {
+   solidity: "0.7.3",
+   defaultNetwork: "rinkeby",
+   networks: {
+      hardhat: {},
+      rinkeby: {
+         url: API_URL,
+         accounts: [`0x${PRIVATE_KEY}`]
+      }
+   },
+}

erc721-solidity-101/package.json

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+{
+  "name": "MiaNFT",
+  "version": "1.0.0",
+  "description": "",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "Mia von Steinkirch",
+  "license": "MIT",
+  "devDependencies": {
+    "@nomiclabs/hardhat-ethers": "^2.0.2",
+    "@nomiclabs/hardhat-waffle": "^2.0.1",
+    "@openzeppelin/contracts": "^3.1.0-solc-0.7",
+    "chai": "^4.3.4",
+    "ethereum-waffle": "^3.4.0",
+    "ethers": "^5.4.6",
+    "hardhat": "^2.6.2"
+  },
+  "dependencies": {
+    "@alch/alchemy-web3": "^1.1.4",
+    "dotenv": "^10.0.0"
+  }
+}

erc721-solidity-101/scripts/deploy-contract.js

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+async function main() {
+    const nft = await ethers.getContractFactory("MiaNFT");
+
+    const nft_deploy = await nft.deploy();
+    console.log("   ⛓🧱✨  Contract address:", nft_deploy.address);
+    console.log("   ➡️      (Please add this string to .env)");
+}
+
+main()
+    .then(() => process.exit(0))
+    .catch(e => {
+        console.error(e);
+        process.exit(1);
+    });

erc721-solidity-101/scripts/mint-nft.js

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+require('dotenv').config();
+
+const PUBLIC_KEY = process.env.PUBLIC_KEY;
+const PRIVATE_KEY = process.env.PRIVATE_KEY;
+const API_URL = process.env.API_URL;
+const METADATA_URL = process.env.METADATA_URL;
+const CONTRACT_ADDRESS = process.env.CONTRACT_ADDRESS;
+const { createAlchemyWeb3 } = require("@alch/alchemy-web3");
+const web3 = createAlchemyWeb3(API_URL);
+const contract = require("../artifacts/contracts/MiaNFT.sol/MiaNFT.json");
+const nftContract = new web3.eth.Contract(contract.abi, CONTRACT_ADDRESS);
+
+async function mintNFT(tokenURI) {
+
+    const nonce = await web3.eth.getTransactionCount(PUBLIC_KEY, 'latest');
+
+    const transaction = {
+        'from': PUBLIC_KEY,
+        'to': CONTRACT_ADDRESS,
+        'nonce': nonce,
+        'gas': 500000,
+        'maxPriorityFeePerGas': 1999999987,
+        'data': nftContract.methods.mintNFT(PUBLIC_KEY, tokenURI).encodeABI()
+    };
+
+    const sign = web3.eth.accounts.signTransaction(transaction, PRIVATE_KEY);
+    sign.then((signedTransaction) => {
+
+    web3.eth.sendSignedTransaction(signedTransaction.rawTransaction, function(e, hash) {
+            if (!e) {
+                console.log("💾 Transaction hash: ", hash);
+            } else {
+                console.log("ERROR:", e)
+            }
+        });
+    }).catch((e) => {
+        console.log("ERROR:", e);
+    });
+}
+
+mintNFT(METADATA_URL);