Javascript 使用push（）时出现mongoose错误

album.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);

app.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]
});

当我使用code

album.songs.push（歌曲）时，我得到错误信息：

无法调用未定义“”的方法“call”

请帮我解决这个问题。如果我想在一张专辑中存储许多歌曲，我该如何做呢？
您混淆了
模式和
模式

在
albums.js
中

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");
});

在
albums.js中

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

所以，解决这个问题的简单方法是在一个文件
models.js
中安装所有模式。是这样吗？你能告诉我如何以你的方式导出模式吗？因为我试图在谷歌上找到答案，但我什么都没有，也许我使用了错误的关键字它正在运行。非常感谢乔。。请帮我解决这个问题
var mongoose = require('mongoose'),
Schema = mongoose.Schema, 
SongSchema = require('mongoose').model('Song'), // <<<<<<<<<< here should be a schema istead of a model
ObjectId = Schema.ObjectId;

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

SongSchema = require('./songs');