更新子文档中的数组-mongoose mongodb

Question

假设我有一个这样创建的模型：

const attendance = mongoose.Schema({
    studentName: {type: String, required: true},
    status: {type: Number, required: true}
});

const session = mongoose.Schema({
    sessionName: {type: String, required: true},
    attendances: {type: [attendance]}
});

const subjectSchema = mongoose.Schema({
    name: {type: String, required: true},
    faculty_ID: {type: String, required: true},
    students: {type: [String]},
    sessions: {type:[session]} 
});

module.exports = mongoose.model('Subject', subjectSchema);

样本文件如下所示：

{
    students: [
        "Student1",
        "Student2",
        "Student3"
    ],
    _id: "5bd5a6f49097cd505cf6317a",
    name: "subjectName",
    faculty_ID: "5bd57383bbe10f4f6439ae43",
    sessions: [
        {
            attendances: [ ],
            _id: "5bd6c4de95ffe03480ee8796",
            sessionName: "Session1"
        },
        {
            attendances: [ ],
            _id: "5bd7a9d2604b760004947833",
            sessionName: "Session2"
        },
        {
            attendances: [ ],
            _id: "5bd7a9e4604b760004947834",
            sessionName: "Session3"
        }
    ]
}

在会话内的出席者数组之一中推送新元素的最佳方法是什么？

就像我想推这个：

{
    studentName: "Student1",
    status: "Present"
}

插入到具有sessionName: "Session1"的对象的出席者数组中，这样文档将如下所示：

{
    students: [
        "Student1",
        "Student2",
        "Student3"
    ],
    _id: "5bd5a6f49097cd505cf6317a",
    name: "subjectName",
    faculty_ID: "5bd57383bbe10f4f6439ae43",
    sessions: [
        {
            attendances: [
               {
                   studentName: "Student1",
                   status: "Present"
               }
            ],
            _id: "5bd6c4de95ffe03480ee8796",
            sessionName: "Session1"
        },
        {
            attendances: [ ],
            _id: "5bd7a9d2604b760004947833",
            sessionName: "Session2"
        },
        {
            attendances: [ ],
            _id: "5bd7a9e4604b760004947834",
            sessionName: "Session3"
        }
    ]
}

另外，如果我已经成功地将新元素推入该数组，那么如何删除该数组上的特定元素？

Answer 1

您可以使用$位置运算符来指示应修改的session 。 尝试：

Model.updateOne({ _id: "5bd5a6f49097cd505cf6317a", "sessions._id": "5bd6c4de95ffe03480ee8796" }, 
    { $push: { "sessions.$.attendances": {  studentName: "Student1", status: "Present" } } })

要删除该值，您需要使用相同的运算符和$ pull （以condition为参数），例如：

Model.updateOne({ _id: "5bd5a6f49097cd505cf6317a", "sessions._id": "5bd6c4de95ffe03480ee8796" }, 
    { $pull: { "sessions.$.attendances": {  studentName: "Student1" } } })