如何通过两个引用更新数组中的单个子元素

Question

I have a school document structure like this:

{
    "_id":"tnoMB2PhsPPQKcafz",
    // some other property here
    "students":[{
        "student":{
            "ref_id":"eaH7JsponapSWCGf6",
            "name":"name",
            "family":"family",
            "grade":12
        },
        // many other student here
]}

I want to update grade property for determined student in determined school but I don't know how to do this.

For example I have school _id ( tnoMB2PhsPPQKcafz ) and student ref_id ( eaH7JsponapSWCGf6 ) and want to update determined student grade from 12 to 18.

Answer 1

使用$elemMatch如下：

db.school.update({"_id" : "tnoMB2PhsPPQKcafz","students":{"$elemMatch":{"student.ref_id":"eaH7JsponapSWCGf6"}}},{"$set":{"students.$.student.grade":18}})