custom CRUD in loopback remote-method for collection other than model for mongodb

I am using Loopback for my project. I created a Model 'test' and a remote-method 'createOrder' for the test model.

'use strict';

module.exports = function (Test) {
    /**
     * 
     * @param {number} amount 
     * @param {Function(Error)} callback
     */

    Test.createOrder = function (amount, callback) {
        // Add log to the logs collection 
        callback(null);
    };
};

I am using MongoDB as datasource.

{
  "db": {
    "name": "db",
    "connector": "memory"
  },
  "paymentDS": {
    "host": "localhost",
    "port": 27017,
    "url": "",
    "database": "test",
    "password": "",
    "name": "testDS",
    "user": "",
    "useNewUrlParser": true,
    "connector": "mongodb"
  }
}

I want to insert logs into logs collection from the createOrder remote-method defined in test model. How can I do that?

from custom CRUD in loopback remote-method for collection other than model for mongodb