Node.js 如何在JavaScript中使用Mongoose将项推送到MongoDB中的重嵌套数组

我正在try 建立一个使用Express JS和reactJS的消息传递站点. 我目前正在开发该网站的消息发送功能.我的目标是，当用户单击Reaction页面上的Send按钮时，它向Express后端发出POST请求，后者将消息数据推送到我的MongoDB Altlas集合中正确用户的"Messages"array.问题是我不知道如何将消息推送到正确用户的数组中，因为它与集合中的其他数据嵌套在一起. 有谁可以帮我？

以下是我坚持使用的index.js快速代码:

const userSchema = new mongoose.Schema({
    name: String,
    password: String,
    profilePicture: String,
    contacts: [{name: String, 
        profilePicture: String, 
        messages: [{sender: String, message: String}], 
    }]
});
const User = new mongoose.model('User', userSchema);


app.post("/send-message", (req, res) => {
    var sender = req.body.sender;
    var recv = req.body.recv;
    var message = req.body.msg
    User.findOne({name: sender}).then(user => {
        user.contacts.forEach(contact => {
            if (contact.name === recv){
                // newMessage is the object I would like to push to the 
                // messages array for the sender.
                var newMessage = {sender: "me", message: message};
            }
        });
    }).then(() => {
        User.findOne({name: recv}).then(user => {
            user.contacts.forEach(contact => {
                if (contact.name === sender){
                    // newMessage is the object I would like to push to 
                    // the messages array for the receiver.
                    var newMessage = {sender: "them", message: message};
                }
            });
        }).then(res.send("Message Sent!"))
        .catch(e => {console.log("2: " + e); res.send("Error!")});
    }).catch(e => {console.log("1: " + e); res.send("Error!")});
});

下面是我对SendMessage函数的react 代码:

const [usrn, setUsrn] = React.useState("<Username>");
const [pass, setPass] = React.useState("<Password>");
const [messageThread, setMessageThread] = React.useState({});
const [message, setMessage] = React.useState("");

const SendMessage = () => {
        axios.post(props.apiUrl + "send-message/", {sender: usrn, recv: 
                   messageThread.contact, msg: message})
        .then(res => {
            console.log(res.data);
            setMessage("");
        });
    }