无法更新猫鼬中的对象

我正在尝试以我的顺序模式更新对象,状态已正确更新,但 latestStatusUpdates 不是。以下是我的订单模式的重要部分:

status: {
    type: String,
    enum: ["pending", "processing", "delivered", "cancelled"],
    default: "pending",
},
latestStatusUpdates: {
    type: {
        pending: Date,
        processing: Date,
        delivered: Date,
        cancelled: Date,
    },
    default: {
        pending: "",
        processing: "",
        delivered: "",
        cancelled: "",
    },
},

以下是我更新属性的方式:

    const orderId = req.params.id;
    const newStatus = req.body.status;
    
    const order = await Order.findById(orderId);

    if (!order) {
        return res.status(404).send({
            message: "Order not found.",
        });
    }

    
    const today = new Date();

    order.status = newStatus; // This is updating correctly

    order.latestStatusUpdates[newStatus] = today; // This is not updating

    await order.save();

    res.status(200).send({
        message: "Order Updated Successfully!",
})