如何为智能合约添加创建时间？

Question

我正在为患者记录编写智能合约。但数据将采用时间序列数据格式。我想我应该为此添加 created_at 字段。但是我不知道具体怎么做。

我是这份工作的新手。你能帮帮我吗？

可以看到部分结构：

    struct Patient {
        string name;
        uint16 age;
        //max of uint16 is 4096
        //if we use uint8 the max is uint8
        string telephone;
        string homeAddress;
        uint64 birthday; //unix time
        string disease; //disease can be enum
        Gender gender;
    }

Answer 1

您可以使用 block.timestamp 关键字将当前块时间戳设置为自包含您的交易的 unix 纪元以来的秒数。

有关block.timestamphere的更多信息。

您必须将 createdAt 变量设置为结构：

struct Patient {
  string name;
  uint16 age;
  //max of uint16 is 4096
  //if we use uint8 the max is uint8
  string telephone;
  string homeAddress;
  uint64 birthday; //unix time
  string disease; //disease can be enum
  Gender gender;
  // NOTE: createdAt variable
  uint createdAt
}

然后你必须使用这个语句来设置这个变量：

[your_struct_variable] = block.timestamp;

智能合约代码示例：

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract Hospital {

    enum Gender { MALE, FEMALE }

    struct Patient {
        string name;
        uint16 age;
        //max of uint16 is 4096
        //if we use uint8 the max is uint8
        string telephone;
        string homeAddress;
        uint64 birthday; //unix time
        string disease; //disease can be enum
        Gender gender;
        uint256 createdAt;
    }

    mapping(address => Patient) _patients;

    function setPatients() public {
        Patient memory _patient = Patient({
            name: "test",
            age: 50,
            telephone: "test",
            homeAddress: "test",
            birthday: 1010101010,
            disease: "test",
            gender: Gender.MALE,
            createdAt: block.timestamp            
        });
        _patients[msg.sender] = _patient;
    }

    function getPatient() external view returns(Patient memory) {
        return _patients[msg.sender];
    }

}

如何为智能合约添加创建时间？

How can I add a created at for smart contract?

database

blockchain

solidity

smartcontracts

remix