貓鼬錯誤時使用推送（）

Question

 
-- express_example 
|---- app.js 
|---- models 
|-------- songs.js 
|-------- albums.js 
|---- and another files of expressjs 

songs.js：

var mongoose = require('mongoose'), 
    Schema = mongoose.Schema, 
    ObjectId = Schema.ObjectId; 

var SongSchema = new Schema({ 
    name: {type: String, default: 'songname'}, 
    link: {type: String, default: './data/train.mp3'}, 
    date: {type: Date, default: Date.now()}, 
    position: {type: Number, default: 0}, 
    weekOnChart: {type: Number, default: 0}, 
    listend: {type: Number, default: 0} 
}); 
module.exports = mongoose.model('Song', SongSchema); 

album.js：

var mongoose = require('mongoose'), 
    Schema = mongoose.Schema, 
    SongSchema = require('mongoose').model('Song'), 
    ObjectId = Schema.ObjectId; 

var AlbumSchema = new Schema({ 
    name: {type: String, default: 'songname'}, 
    thumbnail: {type:String, default: './images/U1.jpg'}, 
    date: {type: Date, default: Date.now()}, 
    songs: [SongSchema] 
}); 

app.js：

require('./models/users'); 
require('./models/songs'); 
require('./models/albums'); 

var User = db.model('User'); 
var Song = db.model('Song'); 
var Album = db.model('Album'); 

var song = new Song(); 
song.save(function(err){ 
    if(err) { throw err; } 
    console.log("song saved"); 
}); 

var album = new Album(); 
album.songs.push(song); 

album.save(function(err){ 
    if(err) { throw err; } 
    console.log("save album"); 
}); 

當我使用代碼album.songs.push(song);，我收到錯誤：

Cannot call method 'call' of undefined`.

請幫我解決這個問題。如果我想在專輯中存儲很多歌曲，我應該怎麼做？

Answer 1

你一頭霧水，之間modelschema

在 albums.js

，

var mongoose = require('mongoose'), 
Schema = mongoose.Schema, 
SongSchema = require('mongoose').model('Song'), // <<<<<<<<<< here should be a schema istead of a model 
ObjectId = Schema.ObjectId; 

一個辦法解決它是嘗試出口SongSchema在songs.js，然後要求其在albums.js

在 songs.js

：

mongoose.model('Song', SongSchema); // This statement registers the model 
module.exports = SongSchema; // export the schema instead of the model 

在albums.js

SongSchema = require('./songs');