Mongodb $push 运算符不起作用

Posted 2023-03-11

【中文标题】Mongodb $push 运算符不起作用

【英文标题】：Mongo db $push operator not working

【发布时间】：2018-04-27 08:33:35

【问题描述】：

我正在尝试将数据推送到 mongo 模型中对象的数组中 通过使用 req.params 方法 但它给了我 错误：

MongoError：无法使用部分（friends of friends.username）遍历元素（friends:[]）

这是我的代码：

后端

  router.post('/accept/:id/:username',isLoggedIn,function(req,res)
              User.findOneAndUpdate(username:req.user.username,'friendRequest._id':req.params.id,
              $set:'friendRequest.$.Status':'Friend','friendRequest.$.Color':'green',function(err,founduser)

                if (err) 
                  throw err;
                 else 

               User.findOneAndUpdate(username:req.user.username,
               $push:'friends.username':req.params.username
               ,function(err,founduser)

                 if (err) 
                  throw err;
                 else 

//Error is coming from this line
                User.findOneAndUpdate(username:req.params.username,
                $push:'friends.username':req.user.username
                ,function(err,founduser)

                     if (err) 
                      throw err;
                     else 
                        res.render("back");
                    
                   )  
                
                   ) 
                   
              )  
            )


**My Model**


            var  mongoose = require('mongoose');
            var passportLocalMongoose = require('passport-local-mongoose');

            var UserSchema = new mongoose.Schema(

            username:String,
            password :String,

              friends:[    
            username: String  //Here I wanna insert a data
            ],

前端

<form  action = "/accept/<%=request._id%>/<%=request.username%>" method = "post"> 
         <button id="add" class="ui  medium  <%=request.Color%> button"><%=request.Status%></button> 
         </form>

【参考方案1】：

需要做一点小改动：

       User.findOneAndUpdate(
                username: req.params.username
            , 
                $push: 
                    "friends":
                           username:req.params.username
                                            
                
            ,function(err,founduser)
                 if (err) 
                  throw err;
                 else 
                    res.render("back");
                )