Question

我正在尝试与node.js，Express和MongoDB创建聊天。我有两种猫鼬模型：用于聊天室和消息。

房间型号：

const RoomSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true,
    },
    owner: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Users',
        required: true,
    },

    messages: {
        type: [mongoose.Schema.Types.ObjectId],
        ref: 'Messages',
        required: true,
    },
    users: {
        type: [mongoose.Schema.Types.ObjectId],
        ref: 'Users',
        required: true,
    },


});

const Room = mongoose.model('Rooms', RoomSchema);

消息模型：


const MessageSchema = new mongoose.Schema({
    text: {
        type: String,
        required: true,
    },
    sendBy: {
        type: String,
        required: true
    }

});

const Messages = mongoose.model('Messages', MessageSchema);

以及用于显示所有消息的功能

prepareMessages: function (name, callback) {
        rooms.findOne({
            name: name,
        }).populate('messages')
            .exec(function (err, room) {
                let result = '';
                if (!room) {
                    console.log("Chat does not exist");
                    throw err;
                }
                else {

                    room.messages.forEach(function (item, i, arr) {
                        result += '<dt>' + item.sendBy + '</dt>';
                        result += '<dd>' + item.text + '</dd>';
                    });
                }
                callback(result)
            });
    },

我为什么得到

TypeError: Cannot read property 'sendBy' of undefined？

我尝试了.populate('rooms.messages')，.populate({path: 'rooms.messages', model:'Messages')和其他变体，但仍然无法使用。请帮帮我！

Answer 1

在“房间模式”中，您将消息定义为对象类型为ObjectId的对象，虽然它应该是元素数组，每个元素的类型都是ObjectId，消息应该是对象ID的数组，并且用户以及

const RoomSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true,
    },
    owner: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Users',
        required: true,
    },

    messages: [{ // note here messages is an array
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Messages',
        required: true,
    }],
    users: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Users',
        required: true,
    }],


});

const Room = mongoose.model('Rooms', RoomSchema);

希望有帮助

Answer 2

sendBy应该是ObjectId类型

const MessageSchema = new mongoose.Schema（{ 文字：{ 类型：字符串，必填：是， }， sendBy：{ 类型：mongoose.Schema.Types.ObjectId，必填：true }

}）;

const Messages = mongoose.model（'Messages'，MessageSchema）;

ref应该小写。

ref：“用户”，应更改为ref：“用户”

与其他所有ref相似

猫鼬populate（）返回未定义

2 个答案: