UnhandledPromiseRejectionWarning: MongoError: Cannot create field 'semesters' in element

Question

MongoDB 中的数据库：

{
    "_id" : ObjectId("610144532aa8eb54745f7501"),
    "courses" : [
        {
            "_id" : ObjectId("61014585d71b225516d0116f"),
            "course" : "MBA",
            "semesters" : [
                {
                    "_id" : ObjectId("61014587d71b225516d01174"),
                    "sem" : 1,
                    "subjects" : [ ]
                }
            ]
        }
    ],
    "__v" : 0
}

架构：

const Subject = mongoose.Schema({
    subject : String,
    units : [UnitSchema]
});

我用来在主题数组中添加文档的代码

app.get('/insertSubject', async function(req, res)
{
    const subject = new Subject({
        subject : req.body.subject
    })
    await Padhlo.updateOne(
        {"courses.course":req.body.course , "courses.semesters.sem":parseInt(req.body.semester)},
        {$addToSet : {"courses.semesters.$.subjects":subject}},
        function(err)
        {
            if(!err)
            {
                res.status(200).send("OK");
            }
            else
            {
                res.status(404).send(err);
            }
        }
        )
});

错误：

UnhandledPromiseRejectionWarning: MongoError: Cannot create field 'semesters' in element

我想在 subjects 数组中添加一个文档，但出现此错误，更新后的数据库应该如下所示：

 {
    "_id" : ObjectId("610144532aa8eb54745f7501"),
    "courses" : [
        {
            "_id" : ObjectId("61014585d71b225516d0116f"),
            "course" : "MBA",
            "semesters" : [
                {
                    "_id" : ObjectId("61014587d71b225516d01174"),
                    "sem" : 1,
                    "subjects" : [
                        subject : "BCA",//added new field according to Schema 
                        units : [ ]
                   ]
                }
            ]
        }
    ],
    "__v" : 0
}

请帮助我并告诉我我哪里出错了我是新手，对 mongoDB 我使用的版本 MongoDB : 5.0.1

Answer 1

可以参考MongoDB The all positional operator

The all positional operator $[] indicates that the update operator should modify all elements in the specified array field.

试试这个查询

await Padhlo.updateOne(
    { "courses.course": req.body.course , "courses.semesters.sem": parseInt(req.body.semester) },
    { "$addToSet" : { "courses.$[].semesters.$[].subjects": subject } }
)

UnhandledPromiseRejectionWarning: MongoError: Cannot create field 'semesters' in element

UnhandledPromiseRejectionWarning: MongoError: Cannot create field 'semesters' in element

mongoose

mongodb

node.js

mongoose-schema