以太坊众筹项目合约以及部署01

智能合约众筹实战

###淘宝众筹, 京东众筹
https://izhongchou.taobao.com/index.htm

https://kickstarter.com

###分析商业模式

解决京东众筹的痛点

https://z.jd.com/project/details/105705.html

1. 期望的金钱流动
   

2. 真实的金钱流动
   

控制金钱流动的方向, 速度.

众筹的金钱 进入智能合约中

每一笔开销,都要发起付款申请

投资人support付款申请.

• 带界面的众筹交互项目-React -> 3
• web3js操作以太坊网络 -> 2
• 众筹合约 -> 1

智能合约的其他扩展设计

选举投票决定项目是否继续进行

任何众筹项目都面临团队不负责任或者项目仅仅是一个骗局的风险，任何中心化投票系统都面临安全问题、贿赂选票和其他博弈上的缺陷。在 区块链系统中，这些风险都得到了最小化。

https://baijiahao.baidu.com/s?id=1606757323732765805&wfr=spider

成员变量设计

###函数设计

众筹智能合约的构造函数

pragma solidity ^0.4.17;contract Funding{address public manager;string public projectName;uint public supportMoney;uint public endTime;	uint public goalMoney;address[] public players;function Funding(string _projectName,uint _supportMoney,uint _goalMoney) public{projectName = _projectName;supportMoney = _supportMoney;goalMoney = _goalMoney;endTime = now + 4 weeks;manager = msg.sender;} 
}

众筹支持逻辑

	address[] public players;function support() public payable{require(msg.value == supportMoney );players.push(msg.sender);}

#测试一下support函数

• 查看当前智能合约余额
• 查看当前众筹参与人员players信息
• 查看当前众筹参与人员players的个数

获取剩余天数

检查众筹状态

付款的Request结构体

struct Request{string description;uint money;address shopAddress;bool complete;}

createRequest

只有经理可以createRequest

    function createRequest(string _description, uint _money, address _shopAddress) public{Request request = Request({description:_description,money:_money,shopAddress:_shopAddress,complete:false});requests.push(request);}

memory和storage

• storage
• memory

##两种概念

1. 智能合约如何存储数据, 是在memory还是storage
2. solidity变量如何存储数据, 是在memory还是在storage

##智能合约的数据存储

1. storage : 成员变量. 可以跨函数调用. 有点类似于硬盘
2. memory: 临时数据存储, 类似于电脑的内存 函数的参数可以理解为memory类型
   

##solidity变量的数据存储
值传递和引用传递
memory值传递
storage引用传递

pragma solidity ^0.4.25;contract Test{uint[] public array;function test() public{array.push(11);array.push(22);// 引用传递 默认是storage, aa修改值会改变原来的数组值uint[] aa = array;aa[0] = 666;// change(array);}// 值传递  默认 memory 内存复制的新对象, arr修改值不会改变原数组function change(uint[] arr) {arr[0] = 888;}// 强制改成storage类型, 必须声明成private, 合约内部函数才可调用, 此时可以修改原数组array的内容function change2(uint[] storage arr) private{arr[0] = 888;}function getArray() public view returns(uint[]) {uint i = 9;return array;}}

投票系统需求

• 防止一个人重复投票
  

• 投票的人可能有很多(成千上万人)

投票系统设计稿 业务逻辑

• 检查某个人是否已经在众筹参与人列表里面

没参与众筹没给钱,投个屁的票啊

• 检查某个人是不是已经投过票了

一人一票不得违反

#投票逻辑的致命问题

有一些小砖（每块1英寸）和大砖（每块5英寸）,我们想砌出来指定长度的墙，
如果用我们选择的砖块的数量能够拼接成功，则返回true；否则返回false，
例如：makeBricks(3, 1, 8) → true

测试用例 (每行显示一条测试用例，格式为(参数1,参数2) -> 期望结果)

[test.suits]
(3, 1, 8) -> true
(3, 1, 9) -> false	
(3, 2, 10) -> true		
(3, 2, 8) -> true	
(3, 2, 9) -> false	
(6, 1, 11) -> true		
(6, 0, 11) -> false	
(1, 4, 11) -> true	
(0, 3, 10) -> true	
(1, 4, 12) -> false	
(3, 1, 7) -> true	
(1, 1, 7) -> false	
(2, 1, 7) -> true	
(7, 1, 11) -> true		
(7, 1, 8) -> true	
(7, 1, 13) -> false	
(43, 1, 46) -> true	
(40, 1, 46) -> false	
(40, 2, 47) -> true	
(40, 2, 50) -> true	
(40, 2, 52) -> false		
(22, 2, 33) -> false	
(0, 2, 10) -> true		
(1000000, 1000, 1000100) -> true	
(2, 1000000, 100003) -> false	
(20, 0, 19) -> true	
(20, 0, 21) -> false	
(20, 4, 51) -> false	
(20, 4, 39) -> true

代码运行的效率 vs 手续费
时间和金钱

#mapping重构代码

pragma solidity ^0.4.17;contract Funding{address public manager;string public projectName;uint public  supportMoney;uint public endTime;	uint public goalMoney;address[] public players;mapping(address => bool) playersMap;Request[] public requests;struct Request{string description;uint money;address shopAddress;bool complete;mapping(address=>bool) approvedPlayers;uint count;}function createRequest(string _description, uint _money, address _shopAddress) public{require(msg.sender == manager);Request memory request = Request({description:_description,money:_money,shopAddress:_shopAddress,complete:false,count:0});requests.push(request);}function approveRequest(uint id) public{require(playersMap[msg.sender]);require(!requests[id].approvedPlayers[msg.sender]);requests[id].count++;requests[id].approvedPlayers[msg.sender] = true;}function finalizeRequest(uint id) public{require(msg.sender == manager);require(requests[id].count*2>players.length);require(requests[id].money<=this.balance);require(!requests[id].complete );requests[id].shopAddress.transfer(requests[id].money);requests[id].complete = true;} function Funding(string _projectName,uint _supportMoney,uint _goalMoney) public{projectName = _projectName;supportMoney = _supportMoney;goalMoney = _goalMoney;endTime = now + 4 weeks;manager = msg.sender;} function support() public payable{require(msg.value == supportMoney );players.push(msg.sender);playersMap[msg.sender] = true;}function getAccountBalance() public view returns(uint){return this.balance;}
}

#智能合约的部署

1. 代理模式, 服务器代理部署(钱服务器花)
2. 用户直接模式, 用户直接部署.(钱用户花)

contract FundingFactory{address[] public fundingAddress; function createFunding(string _projectName,uint _supportMoney,uint _goalMoney) public{address funding = new Funding(_projectName,_supportMoney,_goalMoney,msg.sender);fundingAddress.push(funding);}}

web3js 的函数封装

#附件

第一版
pragma solidity ^0.4.17;contract Funding{bool flag = false;//众筹发起人地址(众筹发起人)address public manager;//项目名称string public projectName;//众筹参与人需要付的钱uint public supportMoney;// 众筹结束的时间  uint public endTime;// 目标募集的资金(endTime后,达不到目标则众筹失败)uint public goalMoney;// 众筹参与人的数组address[] public players;//付款请求申请的数组(由众筹发起人申请)Request[] public requets;// 付款请求的结构体  struct Request{string description; // 为什么要付款 uint money; // 花多少钱 address shopAddress; //  卖家的钱包 地址  bool complete;  //  付款是否已经完成 address[] votedAddress; // 哪些已经投过票的人 uint  voteCount; // 投票的总的总数 }function createRequest( string _description, uint _money, address _shopAddress) public  onlyManagerCanCall{require(this.balance >= _money);Request memory request = Request({description:_description,money:_money,shopAddress:_shopAddress,complete:false,votedAddress: new address[](0),voteCount : 0});requets.push(request);}//  众筹参与人员批准某一笔付款 ( index数组的下标 ) function approveRequest(uint index) public {Request storage request = requets[index];bool supporter = false;//1.  检查某个人是否已经在众筹参与人列表里面for(uint i = 0;i<players.length;i++){if( players[i] == msg.sender){supporter = true;}}require(supporter);//2 .检查某个人是不是已经投过票了bool voted = false;for(uint j = 0; j<request.votedAddress.length;j++){if( request.votedAddress[j] == msg.sender){voted = true;}}require(!voted);request. voteCount ++;request.votedAddress.push(msg.sender);}//  构造函数  function Funding(string _projectName,uint _supportMoney,uint _goalMoney) public{manager = msg.sender;projectName = _projectName;supportMoney = _supportMoney;goalMoney = _goalMoney;endTime = now + 4 weeks;}//  参与人支持众筹 function support() public payable{require(msg.value == 79);players.push(msg.sender);}// 返回参与人的数量 function getPlayersCount() public view returns(uint){return players.length;}function getPlayers() public view returns(address[]){return players;}function getTotalBalance() public view returns (uint){return this.balance;}function getRemainDays() public view returns(uint){return (endTime - now)/24/60/60;}function checkStatus() public {require(!flag);require(now > endTime);require(this.balance > goalMoney);flag = true;}modifier onlyManagerCanCall(){require(msg.sender == manager);_;}}

##全套代码

pragma solidity ^0.4.25;contract FundingFactory {//存储所有已经部署的智能合约的地址 address[] public fundings;function createFunding(string _projectName, uint _supportMoney, uint _goalMoney) public {address funding = new Funding(_projectName, _supportMoney, _goalMoney, msg.sender);fundings.push(funding);}function getFundings() public view returns(address[]){return fundings;}
}contract Funding {// 众筹成功标记bool public flag = false;// 众筹发起人地址(众筹发起人)address public manager;// 项目名称string public projectName;// 众筹参与人需要付的钱uint public supportMoney;// 目标募集的资金(endTime后,达不到目标则众筹失败)uint public goalMoney;// 默认众筹结束的时间,为众筹发起后的一个月uint public endTime;// 众筹参与人的数组address[] public players;mapping(address=>bool) playersMap;// 付款请求的数组Request[] public requests; struct Request {// 描述这笔付款请求是干啥的string description;// 花多少钱, 钱要少于balanceuint money;// 钱汇给谁. 真正的收钱方address shopAddress;// 代表当前付款请求已经处理完毕bool complete;// 已投票的用户地址mapping(address=>bool) votedMap;uint votedCount;} //构造函数constructor(string _projectName, uint _supportMoney, uint _goalMoney, address sender) public{manager = sender;projectName =_projectName;supportMoney = _supportMoney;goalMoney = _goalMoney;endTime = now + 4 weeks;}// 我要支持(需要付钱)function support() public payable{require(msg.value == supportMoney);// 放进集合中players.push(msg.sender);playersMap[msg.sender] = true;}// 付款申请函数,由众筹发起人调用function createRequest(string _description, uint _money, address _shopAddress) public onlyManagerCanCall{// 余额大于等于付款请求 require(address(this).balance >= _money);Request memory request = Request({description: _description,money: _money,shopAddress: _shopAddress,complete: false,votedCount: 0});requests.push(request);}// 付款批准函数, 由众筹参与人调用function approveRequest(uint index) public {// 是否是众筹参与者require(playersMap[msg.sender]);// 防止一个人重复投票Request storage request = requests[index];require(!request.votedMap[msg.sender]);request.votedMap[msg.sender] = true;request.votedCount++;}// 众筹发起人调用, 可以调用完成付款function finalizeRequest(uint index) public onlyManagerCanCall{Request storage request = requests[index];require(!request.complete);// 钱够require(address(this).balance >= request.money);// 人数过半require(request.votedCount * 2 >= getPlayersCount());// 执行转账操作request.shopAddress.transfer(request.money);request.complete = true;}// 所有参与者function getPlayers() public view returns(address[]){return players;}// 所有参与者个数function getPlayersCount() public view returns(uint){return players.length;}// 获取合约的余额function getTotalBalance() public view returns(uint){return address(this).balance;}// 获取剩余天数function getRemainDays() public view returns(uint) {return (endTime - now) / 60 / 60 / 24;}// 检查众筹状态function checkStatus() public onlyManagerCanCall {require(!flag);// 到期require(now >= endTime);// getTotalBalance金额>= goalMoneyrequire(address(this).balance >= goalMoney);flag = true;}modifier onlyManagerCanCall {require(msg.sender == manager);_;}}

• es6 大神阮一峰的文章 http://es6.ruanyifeng.com/#docs/module#export-default-命令
• 代码战争: https://www.codewars.com