Solidity中如何實現復雜的交易邏輯

在Solidity中實現復雜的交易邏輯，通常需要編寫多個函數和結構體，并利用Solidity的高級特性，如函數修飾符、事件、異常處理等。以下是一些關鍵步驟和示例代碼，幫助你理解如何在Solidity中實現復雜的交易邏輯：

1. 定義結構體和映射

首先，你可以使用結構體來組織相關的數據，并使用映射（mapping）來存儲和查詢數據。

struct Transaction {
    address sender;
    address receiver;
    uint256 amount;
    bool isCompleted;
}

mapping(uint256 => Transaction) public transactions;

2. 編寫函數

接下來，你可以編寫函數來處理交易的創建、更新和查詢等操作。

pragma solidity ^0.8.0;

contract ComplexTransaction {
    struct Transaction {
        address sender;
        address receiver;
        uint256 amount;
        bool isCompleted;
    }

    mapping(uint256 => Transaction) public transactions;

    event TransactionCreated(uint256 indexed id, address indexed sender, address indexed receiver, uint256 amount);
    event TransactionCompleted(uint256 indexed id);

    function createTransaction(address _receiver, uint256 _amount) public payable {
        require(msg.value == _amount, "Amount sent does not match the specified amount.");
        transactions[transactions.length] = Transaction(_sender, _receiver, _amount, false);
        emit TransactionCreated(transactions.length, _sender, _receiver, _amount);
    }

    function completeTransaction(uint256 _id) public {
        require(transactions[_id].sender == msg.sender, "You are not authorized to complete this transaction.");
        require(!transactions[_id].isCompleted, "Transaction already completed.");
        transactions[_id].isCompleted = true;
        emit TransactionCompleted(_id);
    }

    function getTransactionCount() public view returns (uint256) {
        return transactions.length;
    }

    function getTransactionDetails(uint256 _id) public view returns (address, address, uint256, bool) {
        require(transactions[_id].isCompleted, "Transaction not completed yet.");
        return (transactions[_id].sender, transactions[_id].receiver, transactions[_id].amount, transactions[_id].isCompleted);
    }
}

3. 使用修飾符

你可以使用修飾符來限制函數的訪問權限，例如只允許特定地址調用某些函數。

pragma solidity ^0.8.0;

contract ComplexTransaction {
    struct Transaction {
        address sender;
        address receiver;
        uint256 amount;
        bool isCompleted;
    }

    mapping(uint256 => Transaction) public transactions;

    event TransactionCreated(uint256 indexed id, address indexed sender, address indexed receiver, uint256 amount);
    event TransactionCompleted(uint256 indexed id);

    modifier onlySender(uint256 _id) {
        require(transactions[_id].sender == msg.sender, "You are not the sender of this transaction.");
        _;
    }

    function createTransaction(address _receiver, uint256 _amount) public payable {
        require(msg.value == _amount, "Amount sent does not match the specified amount.");
        transactions[transactions.length] = Transaction(msg.sender, _receiver, _amount, false);
        emit TransactionCreated(transactions.length, msg.sender, _receiver, _amount);
    }

    function completeTransaction(uint256 _id) public onlySender(_id) {
        require(!transactions[_id].isCompleted, "Transaction already completed.");
        transactions[_id].isCompleted = true;
        emit TransactionCompleted(_id);
    }

    function getTransactionCount() public view returns (uint256) {
        return transactions.length;
    }

    function getTransactionDetails(uint256 _id) public view returns (address, address, uint256, bool) {
        return (transactions[_id].sender, transactions[_id].receiver, transactions[_id].amount, transactions[_id].isCompleted);
    }
}

4. 異常處理

在Solidity中，你可以使用require語句來處理異常情況，確保合約的邏輯正確執行。

pragma solidity ^0.8.0;

contract ComplexTransaction {
    struct Transaction {
        address sender;
        address receiver;
        uint256 amount;
        bool isCompleted;
    }

    mapping(uint256 => Transaction) public transactions;

    event TransactionCreated(uint256 indexed id, address indexed sender, address indexed receiver, uint256 amount);
    event TransactionCompleted(uint256 indexed id);

    modifier onlySender(uint256 _id) {
        require(transactions[_id].sender == msg.sender, "You are not the sender of this transaction.");
        _;
    }

    function createTransaction(address _receiver, uint256 _amount) public payable {
        require(msg.value == _amount, "Amount sent does not match the specified amount.");
        transactions[transactions.length] = Transaction(msg.sender, _receiver, _amount, false);
        emit TransactionCreated(transactions.length, msg.sender, _receiver, _amount);
    }

    function completeTransaction(uint256 _id) public onlySender(_id) {
        require(!transactions[_id].isCompleted, "Transaction already completed.");
        transactions[_id].isCompleted = true;
        emit TransactionCompleted(_id);
    }

    function getTransactionCount() public view returns (uint256) {
        return transactions.length;
    }

    function getTransactionDetails(uint256 _id) public view returns (address, address, uint256, bool) {
        require(transactions[_id].isCompleted, "Transaction not completed yet.");
        return (transactions[_id].sender, transactions[_id].receiver, transactions[_id].amount, transactions[_id].isCompleted);
    }
}

通過以上步驟和示例代碼，你可以在Solidity中實現復雜的交易邏輯。根據具體需求，你可以進一步擴展和優化這些代碼。