Laravel 5.4 with mongodb: how to query data from multiple collection by using reference id

Question

Here are the collections I'm working with

Fee package collection

{
    "_id": ObjectId("591abc701c9dfa0a6e7608e6"),
    "fee_package_name": "abc",
    "fee_structure": [{
            "fee_name": "Fee1",
            "fee_amount": 1550
        },
        {
            "fee_name": "Fee2",
            "fee_amount": 1750
        },
        {
            "fee_name": "Fee3",
            "fee_amount": 550
        }
    ],
    "total_fee_amount": 3850.0,
}

Student fee collection

{
    _id: ObjectId("585a98d7fc6c0468218267f9"),
    applied_fee_packages: [
        {
            fee_package_id: ObjectId("591abc701c9dfa0a6e7608e6"),
            applied_discount: 0
        },
        {
            fee_package_id: ObjectId("591abc701c9dfa0a6e7608e7"),
            applied_discount: 0
        }
    ]
}

Laravel: Model: FeePackage:

use Jenssegers\Mongodb\Eloquent\Model as Eloquent;

class FeePackage extends Eloquent
{
    protected $collection = 'fee_packages';


    public function studentFee() {
        return $this->belongsTo('App\Models\StudentFee');
    }
}

Laravel: Model: StudentFee:

use Jenssegers\Mongodb\Eloquent\Model as Eloquent;

class StudentFee extends Eloquent
{
    protected $collection = 'student_fees';    

    public function feePackages() {
        return $this->hasMany('App\Models\FeePackage');
    }
}

I have tried to define hasMany relationship i.e student fee hasMany fee packages and I'm trying to retrieve a student with all fee packages applied to him.

With these documents I get the first student fee like this:

$feeCollection = StudentFee::with('feePackages')->first();

output:

{
    _id: "585a98d7fc6c0468218267f9", 
    fee_packages: []
}

I only get the response without the fee package details for a given student fee id.

Appreciate any pointers to resolve this.

Thanks in advance