如何使用 sub-documents 数组更新 MongoDB 文档

Question

我正在使用 MongoDB 数据库，其 collections 模型 classes、students、学科和[学术]表现。以下是基于 Mongoose 的模式和模型：

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

// SUBJECT collection
var subjectSchema = new Schema({
    name        : { type: String, required: true },
    category    : { type: String, required: true }
});
var Subject = mongoose.model('Subject', subjectSchema);

// STUDENT collection
var studentSchema = new Schema({
    name        : { type: String, required: true },
    grade       : { type: Number, required: true }
});
var Student = mongoose.model('Student', studentSchema);

// PERFORMANCE collection
var performanceSchema = new Schema({
    subjectId   : { type: ObjectId, ref: Subject.modelName, required: true },
    score       : { type: Number, required: true },
    maximum     : { type: Number, required: true },
    grade       : { type: String, required: true }
});
var Performance = mongoose.model('Performance', performanceSchema);

// *Note*: This is just to use as a sub-document schema, and not as a collection
var classStudentSchema = new Schema({
    studentId   : { type: ObjectId, ref: Student.modelName, required: true },
    performance : [performanceSchema]
}, { _id: false });

// CLASS collection
var classSchema = new Schema({
    name        : { type: String, required: true },
    scores      : [classStudentSchema]
});
var Class = mongoose.model('Class', classSchema);

class collection 的文件是这批文件中最复杂的；示例文档为：

{
  "_id" : ObjectId("57758f15f68da08c254ebee1"),
  "name" : "Grade 5 - Section A",
  "scores" : [{
    "studentId" : ObjectId("5776bd36ffc8227405d364d2"),
    "performance": [{
      "subjectId" : ObjectId("577694ecbf6f3a781759c54a"),
      "score" : 86,
      "maximum" : 100,
      "grade" : "B+"
    }, {
      "subjectId" : ObjectId("5776ffe1804540e29c602a62"),
      "score" : 74,
      "maximum" : 100,
      "grade" : "A-"
    }]
  }, {
    "studentId" : ObjectId("5776bd36ffc8227405d364d5"),
    "performance": [{
      "subjectId" : ObjectId("577694ecbf6f3a781759c54a"),
      "score" : 94,
      "maximum" : 100,
      "grade" : "A"
    }, {
      "subjectId" : ObjectId("5776ffe1804540e29c602a62"),
      "score" : 81,
      "maximum" : 100,
      "grade" : "A"
    }]
  }]
}

我能够检索现有的 class 文档并使用以下代码将学生添加到它的分数中：

Class.findOne({ name: 'Grade 5 - Section A' }, function(err, class) {
  if (err) throw err;
  Student.findOne({ name: 'John Doe' }, function(err, student) {
    if (err) throw err;
    class.scores.push({
      studentId: student.id
    });
  };
});

但是我如何 add/update/delete 那个学生的表现呢？我需要能够通过以下方式与 class collection 进行交互：

检索所有学生或特定学生的分数（检索 scores 数组中的特定元素）
为特定科目添加/更新/删除特定学生的分数（在更新或删除的情况下，检索 scores[n].performance 数组中的特定元素；对于添加，追加到同一数组。

Answer 1

有几种方法可以做到这一点我会逐点回答

检索所有学生或特定学生的分数（检索分数数组中的特定元素）

Class.findOne({ name: 'Grade 5 - Section A'})
     .populate('scores.studentId')
     .exec(function(err, class) {
       if (err) throw err;
       //now class.scores.studentId becomes ObjectStudent
       //hence you have all scores for all students
});

为特定科目添加/更新/删除特定学生的分数（如果更新或删除，检索 scores[n].performance 数组中的特定元素；对于添加，追加到同一个数组。

Class.findOneAndUpdate({name: 'Grade 5 - Section A'
                        ,'scores.studentId': ObjectId('5776bd36ffc8227405d364d2')
                        , 'scores.performance.subjectId' : ObjectId('577694ecbf6f3a781759c54a')}
                        , {$set: {scores.performance. score: 50}}
                        , function(err, data) {
           if (err) throw err
    });

希望对你有所帮助

如何使用 sub-documents 数组更新 MongoDB 文档

How to update MongoDB documents with arrays of sub-documents

node.js

mongodb

mongoose

foreign-keys

subdocument