Solidity：在公共方法中返回数组

Question

我试图创建一个返回数组的公共函数，这是错误

返回参数类型映射(uint256 => struct ItemList.Item storage ref) 不能隐式转换为预期类型（第一个返回变量的类型）uint256[] 内存。

pragma solidity ^0.5.0;
contract ItemList {
    uint public itemCount = 0;
    mapping(uint256 => Item) public items;

    event ItemCreated (
        uint id,
        string proofdocument
    );

    struct Item {
        uint id;
        string proofdocument;
    }

    constructor() public {
    }

    function createItem(string memory _proofdocument) public {
        itemCount++;
        items[itemCount] = Item(itemCount, _proofdocument);
        emit ItemCreated(itemCount, _proofdocument);
    }

    function getItems() public pure returns(uint256[] memory ) {
        return items; <----------ERROR
    }
}

谢谢安德里亚

Answer 1

web3.js您可以通过库获取循环中的每个项目

const array = []
for (let i = 0; i < itemCount; itemCount += 1) {
    array.push(contract.getItem(i)) // where getItem do items[I] in solidity
}

或者您可以使用pragma experimental版本：

pragma solidity ^0.5.0;
pragma experimental ABIEncoderV2;

contract ItemList {
    uint public itemCount = 0;

    struct Item {
        uint id;
        string proofdocument;
    }
    Item[] items;

    constructor() public {}

    function createItem(string memory _proofdocument) public {
        itemCount++;
        items.push(Item(itemCount, _proofdocument));
    }

    function getItems() external view returns(Item[] memory) {
        return items;
    }
}