TypeError：無法讀取未定義Mongoose的屬性'推'

Question

我得到下面的錯誤，使用快遞在Node.js中執行應用程序。 我使用的貓鼬爲我的數據庫操作下面我詳細說明了我的設計

Party.js

var mongoose = require("mongoose"); 

var partySchema = new mongoose.Schema({ 
    partyName: String, 
    songs: [ 
     { 
       type: mongoose.Schema.Types.ObjectId, 
       ref: "Song" 
     } 
    ] 
}); 

module.exports = mongoose.model("Party", partySchema); 

Song.js

var mongoose = require("mongoose"); 

var songsSchema = new mongoose.Schema({ 
    videoId: String, 
    videoName: String 
}); 

module.exports = mongoose.model("Song", songsSchema); 

我App.js

app.post("/search/addSong", function(req, res) { 
    Party.find({partyName:"hello"},function(err,party){ 
     if(err){ 
      console.log("Failed in find"); 
     } else { 
      console.log(party); 
      // console.log(typeof(req.body.videoId)); 
      var videoId = req.body.videoId; 

      var newSong = [ { 
       videoId:req.body.videoId, 
       videoName:req.body.videoName 
      } 
      ]; 
      Song.create(newSong, function(err, createdSong){ 
     if(err){ 
      console.log("Error creating a new party"); 
     } else { 
      console.log(createdSong); 
      party.songs.push(createdSong);// ERROR ON THIS LINE 
      party.save(); 
      res.redirect("/search"); 
     } 
    }); 
     } 
    }); 
    res.render("addSong"); 
}); 

當我將歌曲添加到歌曲時，我可以單獨創建派對和歌曲的收藏對象我得到以下錯誤：

TypeError: Cannot read property 'push' of undefined 

任何人都可以請讓我知道我在這裏失蹤.. !!

在此先感謝。

Answer 1

查找返回一個在數組中轉換的遊標。如果您希望獲得單個文檔，請致電findOne。

app.post("/search/addSong", function(req, res) { 
    Party.findOne({partyName:"hello"},function(err,party){ 
     if(err){ 
      console.log("Failed in find"); 
     } else { 
      console.log(party); 
      // console.log(typeof(req.body.videoId)); 
      var videoId = req.body.videoId; 

      var newSong = [ { 
       videoId:req.body.videoId, 
       videoName:req.body.videoName 
      } 
      ]; 
      Song.create(newSong, function(err, createdSong){ 
     if(err){ 
      console.log("Error creating a new party"); 
     } else { 
      console.log(createdSong); 
      party.songs.push(createdSong);// ERROR ON THIS LINE 
      party.save(function(err){ 
      res.redirect("/search"); 
      }); 
     } 
    }); 
     } 
    }); 
    res.render("addSong"); 
}); 

也把節省的回調重定向，它將確保保存完成後僅當重定向被調用，否則將不保存重定向，給人的JavaScript的異步特性。