Execute method for every doc found - node.js

Question

I want to execute isAparticipant method before I send the json data and I dont know the right way to do it and event.find() return a json and not an instance of the model and I think If i do a forEach on evts (JSON data) it's a bad idea.
Controller:
var Event = require('../../model/event');
var eventsController = {
// Get Events List
index: function(req, res){
// var currentUser = req.user;
Event.find(function(err, evts){
if(err){
res.status(400).json({success: false, errors: err.errors});
}else{
res.status(200).json({success: true, events: evts});
}
});
}
};
// Export eventsController
module.exports = eventsController;
Model:
var mongoose = require('mongoose');
var EventsSchema = new mongoose.Schema({
title:{
type: String,
unique: true,
required: true,
},
teaser: {
type: String,
required: true
},
description: {
type: String,
required: true
},
participants: [{type: mongoose.Schema.Types.ObjectId, ref: 'User'}],
start_date: {
type: Date,
required: true
},
end_date: {
type: Date,
required: true
},
lat: {
type: String,
required: true
},
lng: {
type: String,
required: true
},
created_at: {
type: Date,
default: Date.now
},
updated_at: {
type: Date,
default: Date.now
}
});
// Check If User is A particpant
EventsSchema.methods.isAparticipant = function(userId) {
if(this.participants.indexOf(mongoose.Schema.Types.ObjectId(userId)) != -1){
this.isParticipant = true;
}else{
this.isParticipant = false;
}
};
var Evt = mongoose.model('Event', EventsSchema);
module.exports = Evt;

Answer 1

As evts is an array, you can perform a forEach function to loop over the array in a synchronous manner:
evts.forEach(function(evt) {
evt.isParticipant(req.user.id);
});
res.status(200).json({success: true, events: evts});