How do I N-Level mongoose-deep-populate?

Question

I am trying to use mongoose-deep-populate ( https://www.npmjs.com/package/mongoose-deep-populate ) and when I hit the code that invokes it, it only populates one level down

I have done :

npm install mongoose-deep-populate

npm reports back that it installed it:

C:\Users\Documents\GitHub\npm i mongoose-deep-populate
npm WARN uductions@0.0.1 No repository field.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.9 
(node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for     
fsevents@1.2.9: wanted {"os":"darwin","arch":"any"} (current: 
{"os":"win32","arch":"x64"})

+ mongoose-deep-populate@3.1.1
updated 1 package and audited 2727 packages in 9.753s
found 0 vulnerabilities

At the top of my API file, I have this:

const mongoose = require('mongoose');
var deepPopulate = require('mongoose-deep-populate')(mongoose);

here is where I am trying to use deep populate:

Event.findOne({'_id':v.id}).deepPopulate('registration_REF registrations.incentives_REF')
.then(p =>{
    return res.json(p);
})
.catch(p_e =>{
    return res.status(400).json({error: 'unable populate ' + p_e});
})

SCHEMAS

Here is my Event schema (it is in it's respective file)

const EventSchema = new Schema({
    registration_REF: { type: Schema.Types.ObjectId, ref: 'registrations' },
})

// this is required to get rid of exception 
EventSchema.plugin(deepPopulate);

module.exports = Event = mongoose.model('events', EventSchema)

here is the registration schema: (it is in it's respective file)

const RegistrationsSchema = new Schema({    
    dateBeg: {type: Date, required: true},
    dateEnd: {type: Date, required: true},
    incentives_REF: [{ type: Schema.Types.ObjectId, ref: schemaNames.incentives, default: [] }],
})

module.exports = Registration = mongoose.model('registrations', RegistrationsSchema)

Here is incentives Schema: (it is in it's respective file)

const IncentiveSchema = new Schema({
    notificationDays: {type: Number, required: true},
})

module.exports = Incentive = mongoose.model('incentives', IncentiveSchema)

OUTPUT

This is what I get for output when I run the code:

"_id": "5d40a40f93ba712bd43835c8",
"__v": 0,
"registration_REF": {
    "incentives_REF": [
        "5d406e9bc4a3d0110047dc82"
    ],
    "_id": "5d406d237374b00aaca17fdc",
    "dateBeg": "2018-11-29T00:00:00.000Z",
    "dateEnd": "2019-11-29T00:00:00.000Z",
    "__v": 10
}

Answer 1

所以事实证明，我只需要在包含引用中点“包括”该引用：

Event.findOne({'_id':v.id}).deepPopulate('registration_REF.incentives_REF')