Struct containing a (nested) mapping cannot be constructed

Question

function addProductToStore(
    string memory _name,
    string memory _category,
    string memory _imageLink,
    string memory _descLink,
    uint256 _auctionStartTime,
    uint256 _auctionEndTime,
    uint256 _startPrice,
    uint256 _productCondition
) public {
    //开始时间需要小于结束时间
    require(
        _auctionStartTime < _auctionEndTime
        // "开始时间不能晚于结束时间"
    );
    //商品ID自增
    productIndex += 1;
    //product对象稍后直接销毁即可
    Product memory product = Product(
        productIndex,
        _name,
        _category,
        _imageLink,
        _descLink,
        _auctionStartTime,
        _auctionEndTime,
        _startPrice,
        0,
        0,
        0,
        0,
        ProductStatus.Open,
        ProductCondition(_productCondition)
    );
    stores[msg.sender][productIndex] = product;
    productIdInStore[productIndex] = msg.sender;
}

Answer 1

If a struct has nested mapping you should use storage modifier

Product storage product = Product( ...

it means you can't get temporary variable of which struct that contains mapping