无法使用 $push 更新 Mongo DB 对话集合答案

【问题标题】：Unable to update Mongo DB conversation collection by using $push无法使用 $push 更新 Mongo DB 对话集合
【发布时间】：2020-11-28 03:41:16
【问题描述】：

我在这段代码中遇到了一些问题。问题是当我从messages.ejs 发布消息时，MongoDB 集合在profile.ejs 中没有得到更新，一切正常。

profile.ejs

            socket.emit('newMessage', {body: message_text, 
                                        type: "Single",
                                        conv_id: users[0].id + "_" + users[1].id,
                                        users: users,
                                        author_name: message__author_name.val(),
                                        author_avatar: message__author_avatar.val(),
                                        author_id: message__author_id.val(),
                                        added: message__date});

messages.ejs

            socket.emit('newMessage', {body: message_text, 
                                        conv_id: urlParams.get('id'),
                                        author_name: '<%= sessionUser.name %>' + ' ' + '<%= sessionUser.lastname %>',
                                        author_avatar: '<%= sessionUser.avatar %>',
                                        author_id: '<%= sessionUser.id %>',
                                        added: message__date});

我想不是所有的信息都填写在请求中，所以会出现这样的问题，尽管在更新对话集合时甚至不应该添加头像、类型、子组等字段。

                let query = { id: data.conv_id };
                //Check if such conversation exists
                Conversation.find({}, query).count((err, cnt) => {
                    if(cnt > 0) {

                        //If IDs were found, add new messages to the existing conversation
                        Conversation.updateOne(query, {
                                "$push" : {
                                    messages: [
                                        {
                                            body: data.body,
                                            author: data.author_name,
                                            author_id: data.author_id,
                                            author_avatar: data.author_avatar,
                                            attachments: attachments,
                                            added: data.added
                                        }
                                    ]
                                }
                            }, (err) => {
                                if(err) {
                                    throw err;
                                    return;
                                } else {
                                    console.log('Conversation has been updated with new messages');
                                    return;
                                }
                        });
                    } else {
                        //If there's no such IDs, create a new conversation
                        let newMessage = new Conversation({
                            id: data.conv_id,
                            type: data.type,
                            avatar: "defaultConv.png",
                            subgroup: 'all',
                            users: data.users,
                            messages: [
                                {
                                    body: data.body,
                                    author: data.author_name,
                                    author_id: data.author_id,
                                    author_avatar: data.author_avatar,
                                    attachments: attachments,
                                    added: data.added
                                }
                            ]
                        });
                        newMessage.save((err) => {
                            if(err) {
                                console.log(err);
                                return;
                            } else {
                                console.log('Conversation has been created');
                                return;
                            }
                        });
                    }
                });

【问题讨论】：

我认为 find 函数希望查询排在第一位？ Conversation.find(query)
我已经解决了这个问题，请看下面的答案

标签： javascript node.js database mongodb socket.io

【解决方案1】：

我已经解决了这个问题。这都是由于我不注意放置带有 get 方法的 URL 对象造成的。

在messages.ejs 文件中是：

    // When User has clicked send button
    // Sending Message
    let queryString = window.location.search;
    const urlParams = new URLSearchParams(queryString);
    let urlId = urlParams.get('id');

    sendMessage__btn.click(() => {

        ...

        socket.emit('newMessage', {body: message_text, 
                                        conv_id: urlId,
                                        author_name: '<%= sessionUser.name %>' + ' ' + '<%= sessionUser.lastname %>',
                                        author_avatar: '<%= sessionUser.avatar %>',
                                        author_id: '<%= sessionUser.id %>',
                                        added: message__date});

代替：

    sendMessage__btn.click(() => {
        
        // When User has clicked send button
        // Sending Message
        let queryString = window.location.search;
        const urlParams = new URLSearchParams(queryString);
        let urlId = urlParams.get('id');

        ...

        socket.emit('newMessage', {body: message_text, 
                                        conv_id: urlId,
                                        author_name: '<%= sessionUser.name %>' + ' ' + '<%= sessionUser.lastname %>',
                                        author_avatar: '<%= sessionUser.avatar %>',
                                        author_id: '<%= sessionUser.id %>',
                                        added: message__date});

因此，变量 urlId 没有得到更新并返回 null 或不正确的 id

【讨论】：