从0开发一个Dapp
实现效果
房主发送拍卖房屋信息,并且设置拍卖过期时间
2. 其它非房主可以登录进行拍卖,选择自己的出价
参考
https://dev.to/yongchanghe/build-a-simple-dapp-using-truffle-ganache-ethersjs-and-react1-52bl
工具集合
安装node,版本是v16.16.0
npm install -g truffle, truffle可以让我们在本地开发合约,同时部署合约到链上。
安装ganache, ganache相当于是把以太网部署在本地,我们可以把合约发布到本地的以太网上。
metamask,钱包可以添加账户,查看我们的账户余额,
初始化项目
mkdir web3-ticket && truffle init
项目目录如下
修改truffle.config.js的development
4. 打开Ganache,新建workspace,选择项目的trffle.config.js
然后我们就可以看到很多账号了,而且里边还有余额
这样我们就可以通过truffle,连接到链上,同时部署合约到这里了
在web3-ticket/contracts下新建拍卖合约,Auction.sol,代码比较简单,关键地方都已经添加注释。
// SPDX-License-Identifier: MITpragma solidity ^0.8.17;
contract Auction { // Properties // 定义owner地址 address private owner; uint256 public startTime; uint256 public endTime; // 映射 mapping(address => uint256) public bids;
// 结构体 struct House { string houseType; string houseColor; string houseLocation; }
// 最高出价,竞拍,最高价 struct HighestBid { uint256 bidAmount; address bidder; }
House public newHouse; HighestBid public highestBid;
// Insert modifiers here // Modifiers // 竞拍已经结束 modifier isOngoing() { require(block.timestamp < endTime, 'This auction is closed.'); _; } // 竞拍还在进行 modifier notOngoing() { require(block.timestamp >= endTime, 'This auction is still open.'); _; } // 是不是作者,如果不是没有权限 modifier isOwner() { require(msg.sender == owner, 'Only owner can perform task.'); _; } // 不是作者 modifier notOwner() { require(msg.sender != owner, 'Owner is not allowed to bid.'); _; } // Insert events here // Events,允许前端调用事件 event LogBid(address indexed _highestBidder, uint256 _highestBid); event LogWithdrawal(address indexed _withdrawer, uint256 amount); // Insert constructor and function here // Assign values to some properties during deployment constructor () { owner = msg.sender; startTime = block.timestamp; endTime = block.timestamp + 12 hours; newHouse.houseColor = '#FFFFFF'; newHouse.houseLocation = 'Sask, SK'; newHouse.houseType = 'Townhouse'; }
// makeBid 开始竞价,房子必须是在拍卖中,并且不能房主自己出价 function makeBid() public payable isOngoing() notOwner() returns (bool) { uint256 bidAmount = bids[msg.sender] + msg.value; // 当前出价要高于前面的出价,不然报错 require(bidAmount > highestBid.bidAmount, 'Bid error: Make a higher Bid.');
highestBid.bidder = msg.sender; highestBid.bidAmount = bidAmount; bids[msg.sender] = bidAmount; emit LogBid(msg.sender, bidAmount); return true; }
// 付款 function withdraw() public notOngoing() isOwner() returns (bool) { uint256 amount = highestBid.bidAmount; bids[highestBid.bidder] = 0; highestBid.bidder = address(0); highestBid.bidAmount = 0; // 向房主付款 (bool success, ) = payable(owner).call{ value: amount }(""); require(success, 'Withdrawal failed.'); emit LogWithdrawal(msg.sender, amount); return true; } // 获取最高出价 function fetchHighestBid() public view returns (HighestBid memory) { HighestBid memory _highestBid = highestBid; return _highestBid; } // 获得当前房主 function getOwner() public view returns (address) { return owner; }}
执行compile
truffle compile
7. 添加部署文件,在migrations下面添加2_initial_migrations.js
const Auction = artifacts.require("Auction");
module.exports = function (deployer) { deployer.deploy(Auction);};
在test下新建测试文件Auctioin.test.js
const Auction = artifacts.require("Auction");
contract("Auction", async (accounts) => { let auction; const ownerAccount = accounts[0]; const userAccountOne = accounts[1]; const userAccountTwo = accounts[2]; const amount = 5000000000000000000; // 5 ETH const smallAmount = 3000000000000000000; // 3 ETH
beforeEach(async () => { auction = await Auction.new({ from: ownerAccount }); });
it("should make bid.", async () => { await auction.makeBid({ value: amount, from: userAccountOne }); const bidAmount = await auction.bids(userAccountOne); assert.equal(bidAmount, amount); });
it("should reject owner's bid.", async () => { try { await auction.makeBid({ value: amount, from: ownerAccount }); } catch (e) { assert.include(e.message, "Owner is not allowed to bid."); } });
it("should require higher bid amount.", async () => { try { await auction.makeBid({ value: amount, from: userAccountOne }); await auction.makeBid({ value: smallAmount, from: userAccountTwo }); } catch (e) { assert.include(e.message, "Bid error: Make a higher Bid."); } });
it("should fetch highest bid.", async () => { await auction.makeBid({ value: amount, from: userAccountOne }); const highestBid = await auction.fetchHighestBid(); assert.equal(highestBid.bidAmount, amount); assert.equal(highestBid.bidder, userAccountOne); });
it("should fetch owner.", async () => { const owner = await auction.getOwner(); assert.equal(owner, ownerAccount); });});
然后执行
truffle developtest
如果出现下图,说明测试成功
完成后目录文件如下
使用creact-react-app,在web3-ticket目录下
安装依赖
cd clientnpm install ethers @ethersproject/units
修改truuffle.config.js的配置,配置合约的输出目录
发布合约到本地的链上,也就是Ganache模式的链上,因为前面已经启动过了,这里直接发布就可以。
出现下图,说明已经成功部署。
可以看到,部署成功,因为每次需要消耗ETH,所以这里从100ETH到99.98 ETH
同时可以发现在前端的目录client下,增加了contracts目录,如下图
修改client/src/app.js
import "./App.css";import { useEffect, useState } from "react";import { ethers } from "ethers";import { parseEther, formatEther } from "@ethersproject/units";import Auction from "./contracts/Auction.json";// 这里的地址是前面合约部署成功之后的合约地址const AuctionContractAddress = "0xD50acf2Aaa9183b2aC00cd4D27bC3145c919013d";const emptyAddress = "0x0000000000000000000000000000000000000000";
function App() { // Use hooks to manage component state const [account, setAccount] = useState(""); const [amount, setAmount] = useState(0); const [myBid, setMyBid] = useState(0); const [isOwner, setIsOwner] = useState(false); const [highestBid, setHighestBid] = useState(0); const [highestBidder, setHighestBidder] = useState("");
// Sets up a new Ethereum provider and returns an interface for interacting with the smart contract // 使用ethers获取合约 async function initializeProvider() { const provider = new ethers.providers.Web3Provider(window.ethereum); const signer = provider.getSigner(); return new ethers.Contract(AuctionContractAddress, Auction.abi, signer); }
// Displays a prompt for the user to select which accounts to connect // 弹出钱包,让我们选择账户 async function requestAccount() { const account = await window.ethereum.request({ method: "eth_requestAccounts", }); setAccount(account[0]); } // 获取最高出价 async function fetchHighestBid() { if (typeof window.ethereum !== "undefined") { const contract = await initializeProvider(); try { const highestBid = await contract.fetchHighestBid(); const { bidAmount, bidder } = highestBid;
// Convert bidAmount from Wei to Ether and round value to 4 decimal places setHighestBid( parseFloat(formatEther(bidAmount.toString())).toPrecision(4) ); setHighestBidder(bidder.toLowerCase()); } catch (e) { console.log("error fetching highest bid: ", e); } } }
async function fetchMyBid() { if (typeof window.ethereum !== "undefined") { const contract = await initializeProvider(); try { const myBid = await contract.bids(account); setMyBid(parseFloat(formatEther(myBid.toString())).toPrecision(4)); } catch (e) { console.log("error fetching my bid: ", e); } } }
async function fetchOwner() { if (typeof window.ethereum !== "undefined") { const contract = await initializeProvider(); try { const owner = await contract.getOwner(); setIsOwner(owner.toLowerCase() === account); } catch (e) { console.log("error fetching owner: ", e); } } } // 提价出价 async function submitBid(event) { event.preventDefault(); if (typeof window.ethereum !== "undefined") { const contract = await initializeProvider(); try { // User inputs amount in terms of Ether, convert to Wei before sending to the contract. const wei = parseEther(amount); await contract.makeBid({ value: wei }); // Wait for the smart contract to emit the LogBid event then update component state contract.on("LogBid", (_, __) => { fetchMyBid(); fetchHighestBid(); }); } catch (e) { console.log("error making bid: ", e); } } } // 房屋主人获取转账 async function withdraw() { if (typeof window.ethereum !== "undefined") { const contract = await initializeProvider(); // Wait for the smart contract to emit the LogWithdrawal event and update component state contract.on("LogWithdrawal", (_) => { fetchMyBid(); fetchHighestBid(); }); try { await contract.withdraw(); } catch (e) { console.log("error withdrawing fund: ", e); } } }
useEffect(() => { requestAccount(); }, []);
useEffect(() => { if (account) { fetchOwner(); fetchMyBid(); fetchHighestBid(); } }, [account]);
return ( <div style={{ textAlign: "center", width: "50%", margin: "0 auto", marginTop: "100px", }} > {isOwner ? ( <button type="button" onClick={withdraw}> Withdraw </button> ) : ( "" )} <div style={{ textAlign: "center", marginTop: "20px", paddingBottom: "10px", border: "1px solid black", }} > <p>连接的账户是: {account}</p> <p>我的出价: {myBid}</p> <p>拍卖出价最高是: {highestBid}</p> <p> 拍卖出价最高账户是:{" "} {highestBidder === emptyAddress ? "null" : highestBidder === account ? "Me" : highestBidder} </p> {!isOwner ? ( <form onSubmit={submitBid}> <input value={amount} onChange={(event) => setAmount(event.target.value)} name="Bid Amount" type="number" placeholder="Enter Bid Amount" /> <button type="submit">提交</button> </form> ) : ( "" )} </div> </div> );}
export default App;
chrome安装metamask
安装过程比较简单,最主要的是要把钱包的助记词记好
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