node.js - Mongoose - 使用 .populate 访问嵌套对象

Question

架构定义

团队.js

var TeamSchema = new Schema({
    // Team Name.
    name: String,
    lead: String,
    students :type: [{
      block : Number,
      status : String,
      student : {
        type: Schema.ObjectId,
        ref: 'Student'
    }]
});

Student.js

var StudentSchema = new Schema({
   name: String,
   rollNo : Number,
   class : Number
});

我如何填充“学生”以获得输出，如下所示:

团队

{
    "__v": 1,
    "_id": "5252875356f64d6d28000001",
    "students": [
        {
            "__v": 1,
            "_id": "5252875a56f64d6d28000002",
             block : 1,
             status : joined,
            "student": {
                "name": Sumeeth
                "rollNo" : 2
                "class" : 5
            }
        },
        {
            "__v": 1,
            "_id": "5252875a56f64d6d28000003",
            block : 1,
            status : joined,
            "student": {
                "name": Sabari
                "rollNo" : 3
                "class" : 4
            }
        }
    ],
    "lead": "Ratha",   
}

这是我使用 Mongoose 获取文档的 JS:

Team.findOne({
    _id: req.team._id
})            
.populate('students')
.select('students')
.exec(function(err, team) {
    console.log(team);
    var options = {
        path: 'students.student',
        model: 'Student'
    };
    Student.populate(team.students,options,function(err, students) {
        console.log(students);
        if (err) {
            console.log(students);
            res.send(500, {
                message: 'Unable to query the team!'
            });
        } else {
            res.send(200, students);
        }
    });
});

在我的控制台输出中，我得到以下信息:

{ _id: 53aa434858f760900b3f2246,
  students
   [ { block : 1
       status: 'joined'
       _id: 53aa436b58f760900b3f2249 },
     { block : 1
       status: 'joined'
       _id: 53aa436b58f760900b3f2250 }]
}

预期的输出是:

  { _id: 53aa434858f760900b3f2246,
      students
       [ { block : 1
           status: 'joined'
           student :{
              "name": Sumeeth
              "rollNo" : 2
              "class" : 5
           } 
         },
         { block : 1
           status: 'joined'
           student :{
               "name": Sabari
              "rollNo" : 3
              "class" : 4
           } 
        }
     ]
    }

请有人帮我解决我的错误。我应该如何使用 .populate，这样，我才能获得整个学生对象，而不仅仅是它的 id。

引用: Populate nested array in mongoose

Answer 1

我也遇到过同样的问题。我已使用此代码进行救援:

Team.findOne({_id: req.team._id})
.populate({ path: "students.student"})
.exec(function(err, team) {
       console.log(team);
});