Node.js with mongoose delete one array element

Question

I am trying to delete one array element when I click delete button on jade view page.

When clicked, it's going to send selected instructor objected as req.body.

At sever side, it will find courses that contain the instructor objectId.

Any idea for me?

Thank you for reading it.

here is my code:

var id = req.body._id;
clist.find({ instructors: { $in: [id] } }).exec(function (err, result) {
            result.forEach(function (obj) {
                clist.update(
                    { _id: new mongoose.Types.ObjectId(obj._id)},
                    { $pull: { instructors : [new mongoose.Types.ObjectId(id)] } }
                );
                console.log(new mongoose.Types.ObjectId(obj._id) + ' was deleted');
            });
        });

Schema Clist and ilist:

var instructorlist = mongoose.Schema({
    name: { type: String, required: true },
    age: { type: Number, required: true },
    gender: { type: String, required: true },
    DOB: { type: Date, required: true, default: Date.now },
    email: { type: String, required: true },
    phone: { type: Number, required: true },
    address: { type: String, required: true },
    dateofstart: { type: Date, required: true},
    courses: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: "clist"
    }]
});
var courselist = mongoose.Schema({
    coursename: { type: String, required: true },
    coursenumber: { type: String, required: true },
    coursecredit: { type: Number, required: true },
    courseroom: { type: String, required: false },
    courseregisteddate: {type: Date, default: Date.now},
    students: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: "slist"
    }],
    instructors: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: "ilist"
    }]
});

one example for mongodb :

{
    "_id": {
        "$oid": "591a7a3b391a1842e8a69e23"
    },
    "coursename": "JDKD",
    "coursenumber": "COMP4483",
    "coursecredit": 4,
    "courseroom": "sdaf",
    "instructors": [
        {
            "$oid": "591a374422a3a13d38c0bbe5"
        }
    ],
    "students": [],
    "courseregisteddate": {
        "$date": "2017-05-16T04:04:11.848Z"
    },
    "__v": 0
}

When I add instructor objectID in Course.

var newcourse = new clist({
                    'coursename': req.body.coursename, 'coursenumber': req.body.coursenumber, 'coursecredit': req.body.coursecredit
                    , 'courseroom': req.body.room, 'instructors': instructors._id
                });     

Answer 1

Use same operation to find and update multiple

clist.update(
  { instructors: { $in: [id] }},
  { $pull: { instructors : { _id : new mongoose.Types.ObjectId(id) } } }, //or{ $pull: { instructors: mongoose.Types.ObjectId(id) } }
  {
   multi:true
 },
 function(error, success){
  if(error){
   console.log("error",error)

 }
 console.log("success",success)

});