solidity實戰-----撰寫一個簡單的眾籌合約-有解無憂

在學習完solidity編程基礎之后，于是結合課程撰寫了一個簡單的眾籌合約，

【需求分析】

眾籌里面需要有2類角色：接收者和捐贈者，其中接收者可以對應多個捐贈者，下面是這兩類角色屬性分析：

接收者：接收者地址、眾籌總金額、當前眾籌金額、捐贈者的個數

捐贈者：捐贈者地址、捐贈金額

1.接收者

我們按照上面的要求創建了一個接收者物件，里面包含其屬性

    //接收者物件
    struct Recipient{
        address recipient_address; //接收者地址
        uint goal; //籌資金額目標
        uint amount; //當前籌資金額
        uint contributor_amount; //捐贈者數量
        mapping(uint => Contributor) map; //通過id與捐贈者關聯
    }

2.捐贈者

  //捐贈者物件
    struct Contributor{
        address contributor_address; //捐贈者地址
        uint contributor_money; //捐贈金額
    }

3.創建一個眾籌事件

address _address：代表的是當前發起眾籌用戶的地址

uint _goal：代表的是需要籌集的資金總額是多少

    // 發起一個眾籌事件
    function create_crowdfunding(address _address,uint _goal) public {
        // 將接受者id加1
        recipientId++;
        // 創建接受者物件，并通過id與其系結
        recipient_map[recipientId] = Recipient(_address,_goal,0,0);
        
    }

4.為創建眾籌者捐贈

address Newaddress：捐贈者地址

uint _recipientId：接收者的id

    //發起捐贈    
    function contribute(address Newaddress,uint _recipientId) public  payable{
        // 通過id獲取接受者物件
        Recipient storage _recipient = recipient_map[_recipientId];
        // 當前接受者金額加上獲贈的金額
        _recipient.amount += msg.value;
        //捐贈人數加1
        _recipient.contributor_amount++;
        // 將接受者id與捐贈者系結在一起
        _recipient.map[ _recipient.contributor_amount] = Contributor(Newaddress,msg.value);
        
    }

5.判斷眾籌是否完成

通過傳入接收者id來判斷該物件是否完成了眾籌

   // 判斷眾籌任務是否完成
    function Iscompelte(uint _recipientId)public returns(bool){
         // 通過id獲取接受者物件
        Recipient storage _recipient = recipient_map[_recipientId];
        // 判斷籌集資金是否達到與其目標
        if(_recipient.amount >= _recipient.goal){
            //將眾籌到的資金轉移到接受者合約地址
            _recipient.recipient_address.transfer(_recipient.amount);
            return true;
        }
            return false;
        
    }

6.完整代碼

pragma solidity ^0.4.24;

contract crowd_funding{
    
    //捐贈者物件
    struct Contributor{
        address contributor_address; //捐贈者地址
        uint contributor_money; //捐贈金額
    }
    
    //接收者物件
    struct Recipient{
        address recipient_address; //接收者地址
        uint goal; //籌資金額目標
        uint amount; //當前籌資金額
        uint contributor_amount; //捐贈者數量
        mapping(uint => Contributor) map; //通過id與捐贈者關聯
    }
    
    uint public recipientId; //接受者id
    mapping(uint => Recipient) recipient_map; //通過id將接受者資訊關聯
    
    // 發起一個眾籌事件
    function create_crowdfunding(address _address,uint _goal) public {
        // 將接受者id加1
        recipientId++;
        // 創建接受者物件，并通過id與其系結
        recipient_map[recipientId] = Recipient(_address,_goal,0,0);
        
    }
    
    //發起捐贈    
    function contribute(address Newaddress,uint _recipientId) public  payable{
        // 通過id獲取接受者物件
        Recipient storage _recipient = recipient_map[_recipientId];
        // 當前接受者金額加上獲贈的金額
        _recipient.amount += msg.value;
        //捐贈人數加1
        _recipient.contributor_amount++;
        // 將接受者id與捐贈者系結在一起
        _recipient.map[ _recipient.contributor_amount] = Contributor(Newaddress,msg.value);
        
    }
    
    // 判斷眾籌任務是否完成
    function Iscompelte(uint _recipientId)public returns(bool){
         // 通過id獲取接受者物件
        Recipient storage _recipient = recipient_map[_recipientId];
        // 判斷籌集資金是否達到與其目標
        if(_recipient.amount >= _recipient.goal){
            //將眾籌到的資金轉移到接受者合約地址
            _recipient.recipient_address.transfer(_recipient.amount);
            return true;
        }
            return false;
        
    }
  
    
}

7.演示

首先我們運行合約然后點擊部署