Can I use a controller inside another controller?

I'm developing an application, I want to use a controller functions inside another controller function. How can this be done? Or it can't?

Use-case: I want to check in the User collection (using mongoDB) if the user has the permission to post another Patient in the Patient collection. I want to implement somekind of Price Plan approach to my application.

Any doubt or advice, please comment I will gladly answer. Thank you.

user.controller:

'use strict';
/**
 * module dependencies
 */
const User = require('../models/user');
const Utilities = require('../models/utilities');
var errHandler = Utilities.errHandler;
var validationErr = Utilities.validationErr;

module.exports = {
    getAll: getAll,
    put: put,
    post:post,
    deleteUser: deleteUser,
    updateLastLoginDate: updateLastLoginDate,
    get: get,
    patch:patch
}
/**
 * GET user
 */
function get(req, res) {
    if (req.user._id == req.params.id) {
        return User.findById({ _id: req.params.id }, 'email', (err, user) => {
            if (err) {
                return res.status(400);
            }
            if (user) {
                return res.json(user);
            } else {
                return res.status(404);
            }
        });
    } else {
        res.status(403);
    }
}

patient.controller:

'use strict';
/**
 * module dependencies
 */
const Patient = require('../models/patient');
const UserController = require('./user.controller');
const Utilities = require('../models/utilities');
const Logger = require('../config/logger');
var errHandler = Utilities.errHandler;
var validationErr = Utilities.validationErr;

module.exports = {
    getAll: getAll,
    post: post,
    getByNumber: getByNumber,
    getByName: getByName
}
/**
 * Post patient
 * @param id
 */
function post(req, res, done) {
    // Check if user has access to the patient
    if (req.user._id == req.params.id) {
        return Patient.findById({ _id: req.params.id }, (err, patient, done) => {
            if (err) {
                Logger.debug("userId: %s | error:%s | error in finding patient", req.params.id, err);
                return res.status(404);
            }
            var user = UserController.get(req,res);
            Logger.debug("userId: %s | variable %s", req.params.id, a);
            // Do if user.pricePlan.maxPatients < patients.count
            if (patient) {
                patient.name = req.body.name;
                patient.email = req.body.email;
                patient.phoneNumber = req.body.phoneNumber;
            } else {
                var patient = new Patient();
                patient.name = req.body.name;
                patient.registeredIn = new Date();
                patient.phoneNumber = req.body.phoneNumber;
                patient.userId = req.params.id;
            }

            patient.save((err, patient) => {
                if (err) {
                    Logger.debug("userId: %s | error:%s | error in saving patient", req.params.id, err);
                    return res.status(404);
                }
                Logger.debug("userId: %s | patientId: %s | saving patient", req.params.id, patient._id);
                return res.json(patient);
            });
        });
    } else {
        Logger.debug("userId: %s | jwt: %s | trying create patient without permission", req.params.id, req.headers.authorization);
        res.status(403);
    }
}

via Ricardo