食品溯源合约 -- 智能合约实例

前提

Roles: 实现对用户地址的角色权限管控,添加、删除角色。

Producer: 生产商角色管控。

...

FoodInfoItem: 食品信息管控。生产商、中间商、超市添加食品信息。

Trace:食品溯源合约,主要负责对以上几个合约的统筹协作。

Roles

// SPDX-License-Identifier: MIT
pragma solidity >=0.4 <=0.9;//角色库（管理所有角色地址）
// 1. 实现增加角色地址
// 2. 移除角色地址
// 3. 判断角色地址是否被授权
library Roles{struct Role{mapping (address =>bool) bearer;}// 在 Solidity 中，映射（mapping）不能在函数内部声明为局部变量，// 也不能在当前版本（0.8.0）中作为库（library）的成员变量。// 假如role 显示声明storage,那么算是合约中的状态变量,而且不能是memoryfunction add(Role storage role,address account) public {   require(!has(role,account),"Roles:account already has role");role.bearer[account] = true;}function remove(Role storage role,address account) public {require(!has(role,account),"Roles:account has no role ");role.bearer[account] = false;}function has(Role storage role,address account) public  view returns(bool){require(account != address(0),"Roles: account cannot be zero address");return role.bearer[account];}}

Producer

PS:这下面这三个都是代表角色，代码几乎一样的，看会这个，其他都会。

// SPDX-License-Identifier: MIT
pragma solidity >=0.4 <=0.9;
import "./Roles.sol";
/**
*@title Producer
*@dev 
*/
contract Producer {using Roles for Roles.Role;event ProducerAdded(address indexed account);event ProducerRemoved(address indexed account);Roles.Role private _producers; // 使用这个相当于使用库constructor(address producer){ // 初始化给账户添加权限_addProducer(producer);}// 关于下面这几个函数为什么要拆分？提高代码可读性。modifier onlyProducer(){require(isProducer(msg.sender),"Producer:caller has no Producer role");_;}// 用户是否拥有权限function isProducer(address account) public view returns (bool) {return _producers.has(account);}function addProducer(address account) public onlyProducer {_addProducer(account); // 不是很理解，为什么设置只有生产者角色才能为地址添加生产者角色权限}function removeRroducer(address account) public  {_removeProducer(account);}function _addProducer(address account) internal {_producers.add(account); // 我们看向Roles的add()其实还有一个参数,但是我们 using for 了那个参数就相当于 _producers本身emit ProducerAdded(account);}function _removeProducer(address account) internal {_producers.remove(account);emit ProducerRemoved(account);}}

Retailer

// SPDX-License-Identifier: MIT
pragma solidity >=0.4 <=0.9;
import "./Roles.sol";// 超市
contract Retailer {using Roles for Roles.Role;event RetailerAdded(address indexed account);event RetailerRemoved(address indexed account);Roles.Role private _retailers; // 使用这个相当于使用库constructor(address retailer){ // 初始化给账户添加权限_addRetailer(retailer);}// 关于下面这几个函数为什么要拆分？提高代码可读性。modifier onlyRetailer(){require(isRetailer(msg.sender),"Retailer:caller has no Retailer role");_;}// 用户是否拥有权限function isRetailer(address account) public view returns (bool) {return _retailers.has(account);}function addRetailer(address account) public onlyRetailer {_addRetailer(account); }function removeRroducer(address account) public  {_removeRetailer(account);}function _addRetailer(address account) internal {_retailers.add(account); // 我们看向Roles的add()其实还有一个参数,但是我们 using for 了那个参数就相当于 _Retailers本身emit RetailerAdded(account);}function _removeRetailer(address account) internal {_retailers.remove(account);emit RetailerRemoved(account);}}

Distributor

// SPDX-License-Identifier: MIT
pragma solidity >=0.4 <=0.9;
import "./Roles.sol";
// 中间商
contract Distributor {using Roles for Roles.Role;event DistributorAdded(address indexed account);event DistributorRemoved(address indexed account);Roles.Role private _distributors; // 使用这个相当于使用库constructor(address distributor){ // 初始化给账户添加权限_addDistributor(distributor);}// 关于下面这几个函数为什么要拆分？提高代码可读性。modifier onlyDistributor(){require(isDistributor(msg.sender),"Distributor:caller has no Distributor role");_;}// 用户是否拥有权限function isDistributor(address account) public view returns (bool) {return _distributors.has(account);}function addDistributor(address account) public onlyDistributor {_addDistributor(account); }function removeRroducer(address account) public  {_removeDistributor(account);}function _addDistributor(address account) internal {_distributors.add(account); // 我们看向Roles的add()其实还有一个参数,但是我们 using for 了那个参数就相当于 _Distributors本身emit DistributorAdded(account);}function _removeDistributor(address account) internal {_distributors.remove(account);emit DistributorRemoved(account);}}

FoodInfoItem

// SPDX-License-Identifier: MIT
pragma solidity >=0.4 <=0.9;
pragma experimental ABIEncoderV2;//食品信息管理合约
// 1.	保存食品基本信息:时间戳(流转过程中),用户名(流转过程中),用户地址信息(流转过程中),食品质量(流转过程中),食物名称,当前用户名称,质量,状态.
// 2.	对食品基本信息进行初始化
// 3.	实现两个方法:中间商添加食品信息;超市添加食品信息
// 4.	实现显示食品信息的方法contract FoodInfoItem {uint[] _timestamp;     //保存食品流转过程中各个阶段的时间戳string[] _traceName;    //保存食品流转过程各个阶段的用户名address[] _traceAddress; //保存食品流转过程各个阶段的用户地址信息（和用户一一对应）uint8[] _traceQuality;  //保存食品流转过程中各个阶段的质量string _name;  //食品名称string _currentTraceName;  //当前用户名称uint8 _quality; //质量（0=优质 1=合格 2=不合格）uint8 _status; //状态（0:生产 1:分销 2:出售）address  _owner;// 初始化食品,创建者是生产商constructor(string memory name,string memory traceName,uint8 quality,address producer) public  {_name = name;_currentTraceName = traceName;_quality = quality;_owner = producer;_status = 0;// 不多说，看上面状态变量都能明白_timestamp.push(block.timestamp); _traceName.push(traceName);_traceAddress.push(producer);_traceQuality.push(quality);}// 中间商添加食品信息function addTraceInfoByDistributor(string memory traceName,uint8 quality,address distributor) public returns(bool){require(_status == 0, "FoddIndo: caller must be distributor");_currentTraceName = traceName;_quality = quality;_status = 1;_timestamp.push(block.timestamp); _traceName.push(traceName);_traceAddress.push(distributor);_traceQuality.push(quality);return true;}// 超市添加食品信息function addTraceInfoByRetailer(string memory traceName,uint8 quality,address retailer)public returns(bool){require(_status == 1, "FoddIndo: caller must be retailer");_currentTraceName = traceName;_quality = quality;_status = 2;_timestamp.push(block.timestamp); _traceName.push(traceName);_traceAddress.push(retailer);_traceQuality.push(quality);return true;}// 拿到食品流转的全部信息function getTraceInfo() public view  returns(uint[] memory,string[] memory,address[] memory,uint8[] memory){return (_timestamp,_traceName,_traceAddress,_traceQuality);}// 拿到生产商一开始添加食品信息function getFood() public view returns(uint,string memory,address,uint8,string memory){return (_timestamp[0],_traceName[0],_traceAddress[0],_traceQuality[0],_name);}}

Trace

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.9.0;
pragma experimental ABIEncoderV2; // 开启实验性功能，包括对map,数组的编码和解码等
import "./FoodInfoItem.sol";
import "./Distributor.sol";
import "./Producer.sol";
import "./Retailer.sol";//食品溯源合约（负责具体食品溯源信息的生成）
//  1.实现生产食品的方法(新建食品信息)
//  2.实现食品分销过程中增加溯源信息的接口
//  3.实现食品出售过程中增加溯源信息的接口
//  4.实现获取食品溯源信息接口contract Trace is Distributor,Producer,Retailer {mapping(uint256 => address) foods; //食品溯源id到 -> 具体食品溯源合约的映射表uint[] foodList; // 食品溯源id数组//构造函数初始化,一起把父类角色初始化constructor(address producer,address distributor,address retailer)    Producer(producer) Distributor(distributor) Retailer(retailer) {}// 生产商调用，调用添加食品信息function newFood(string memory name,uint256 traceNumber, // 溯源idstring memory traceName,uint8 quality) public onlyProducer returns (address) {require(foods[traceNumber] == address(0), "Trace:traceNumber already exist"); // 检测溯源id对应食品合约是否已经存在,已存在id不能用。FoodInfoItem food = new FoodInfoItem( // 初始化食品合约name,traceName,quality,msg.sender);foods[traceNumber] = address(food); // 往映射表添加地址foodList.push(traceNumber); // 往食品溯源数组添加溯源idreturn address(food);}// 中间商调用,添加食品信息function addTraceInfoByDistributor(uint256 traceNumber,string memory traceName,uint8 quality) public onlyDistributor returns (bool) {require(foods[traceNumber] != address(0), "Trace:traceNumber does not exist"); // id 对应食品合约没存在,代表没食品returnFoodInfoItem(foods[traceNumber]).addTraceInfoByDistributor(traceName,quality,msg.sender); // 调用对应的食品合约方法}// 超市调用,添加食品信息function addTraceInfoByRetailer(uint256 traceNumber,string memory traceName,uint8 quality) public onlyRetailer returns (bool) {require(foods[traceNumber] != address(0), "Trace:traceNumber does not exist");returnFoodInfoItem(foods[traceNumber]).addTraceInfoByRetailer(traceName,quality,msg.sender);}// 拿到所有食品信息function getTraceInfo(uint256 traceNumber) public view returns (uint[] memory,string[] memory,address[] memory,uint8[] memory) {require(foods[traceNumber] != address(0), "Trace:traceNumber does not exist");return FoodInfoItem(foods[traceNumber]).getTraceInfo();}//拿到单条食品信息function getFood(uint256 traceNumber) public view returns (uint,string memory,address,uint8,string memory) {require(foods[traceNumber] != address(0), "Trace:traceNumber does not exist");return FoodInfoItem(foods[traceNumber]).getFood();}// 拿到全部食品的溯源id数组function getAllFood() public view returns (uint[] memory) {return foodList;}}