Batch Update an array in mongoose object - arrays

Question

My Schema is as below. A student can participate in any no. of events.and each Event can have any number of students.
Student{
name:String,
age:Number,
.
.
.,
events:{
type:
[
{type:Schema.ObjectId,
ref:'Event'}
]
}
}
Event{
title:String,
desc:String,
eventDate:Date,
participants:{
type:
[{
student: {type:Schema.ObjectId,
ref:'Student'},
status : String
}]
}
}
My requirement:
Every time,I create an event, I need to push all the participants of that event inside event object. and in turn, tag the event reference inside all the participants.
My code is
function handleTeamParticipants(eventObj, participants) {
Student
.find({
$or: [{
_id: participants[0].student._id
}, {
_id: participants[1].student._id
}]
})
.populate('events events.participants events.participants.student')
.exec(function(err, students) {
var studentLength = students.length,
result = [];
var saveAll = function() {
var doc = students.pop();
Student.populate(doc, {
path: 'events.participants.student',
model: 'Student'
}, function(err, student) {
student.events.push(eventObj);
student.save(function(err, saved) {
if (err) next(err); //handle error
result.push(saved);
if (--studentLength) saveAll();
else // all saved here
{
return res.status(200).send(eventObj);
}
});
});
};
saveAll();
});
}
This code is working.
So, this way, I get only the first two participants updated and in turn added to eventobj. But I want the find query to select all the participants.student._id
Please let me know the easy way to do it.
Thanks.

Answer 1

I used lodash method pluck.
lodash.pluck(< arrayObj >,< attribute >);
will give the list of attribute values in the arrayObj.
studentList = lodash.pluck(pariticipants,"student");
studentIdList = lodash.pluck(studentList,"_id");