php - How to update joinData in cakephp 3 the correct way -

trainers belongstomany customers
both trainerstable , customerstable use user entity class.

i want able update _joindata between 1 trainer , customers.

users +----+-------+--------------------+ | id | level |       email        | +----+-------+--------------------+ |  1 |    30 | trainer@site.com   | |  2 |    10 | customer@site.com  | |  3 |    10 | customer2@site.com | +----+-------+--------------------+  trainers_users +----+------------+-------------+--------------------------+ | id | trainer_id | customer_id |       trainer_note       | +----+------------+-------------+--------------------------+ |  1 |          1 |           2 | customer | |  1 |          1 |           3 |                          | +----+------------+-------------+--------------------------+ 

trainerstable below

<?php namespace app\model\table;  use app\model\entity\user;  class trainerstable extends table {     public function initialize(array $config)     {         $this->table('users');         $this->entityclass('app\model\entity\user'); //since table doesn't follow convention naming         $this->displayfield('id');         $this->primarykey('id');         $this->belongstomany('customers',[             'classname' => 'users',             'jointable' => 'trainers_users',             'foreignkey' => 'trainer_id',             'targetforeignkey' => 'user_id',             ]);     } } 

customerstable below

<?php namespace app\model\table;  use cake\orm\query; use cake\orm\ruleschecker; use cake\orm\table; use cake\validation\validator;  class customerstable extends table {     public function initialize(array $config)     {         $this->belongstomany('trainers',[             'classname' => 'users',             'jointable' => 'trainers_users',             'foreignkey' => 'user_id',             'targetforeignkey' => 'trainer_id',             ]);     } } 

userentity below

<?php namespace app\model\entity;  use cake\orm\entity;  /**  * user entity.  */ class user extends entity {    protected $_accessible = [        'email' => true,        'password' => true,        'trainers' => true,        'level' => true,        'customers' => true,    ]; } 

and interesting part. userscontroller action storenote gets trainer_note , customer_id via ajax. replacelinks way have got working far. how should have done in more sensible way. please give me hints. think i'm on wrong path here.

use app\controller\appcontroller; use cake\event\event; use cake\network\exception\notfoundexception; use cake\orm\tableregistry;  class userscontroller extends appcontroller {    public function initialize()    {         parent::initialize();         //load non standard version of users model trainers         $this->users = tableregistry::get('trainers');    }      /**      * lets trainers store private note each customer,      * trainer can view note customer      */     public function storenote($customerid)     {         if($this->request->is('ajax'))         {             $this->layout = 'ajax';             $this->autorender = false;             $this->response->disablecache();         }         else         {             $this->log('referer request below: ' . $this->request->referer());             throw new forbiddenexception();         }          if ($this->request->is('post')) {             $trainerid = $this->auth->user('id'); //the current user trainer              $trainer = $this->users->find()                                    ->where(['id' => $trainerid])                                    ->contain(['customers'])                                    ->first();             $customers = $trainer->customers; //pick customers              //find index of customer id $customerid             $customerkey = 0;             foreach($customers $key => $singlecustomer)             {                 if ($singlecustomer->id == $customerid) {                     $customerkey = $key;                 }             }              //update trainer_note customer id $customerid             $customers[$customerkey]->_joindata->trainer_note = $this->request->data['trainer_note'];              //replace links             if ($this->users->customers->replacelinks($trainer,$customers)) {                 echo json_encode([  'status' => 'success',                                'redirect' => router::url('/trainer/users/viewcustomer/'.$customerid),                                ]);             } else {                $response = $this->render('/element/trainer/users/store_note');                $html = $response->body();                echo json_encode([  'status' => 'fail',                                    'html' => $html,                                    ]);             }         }         exit();     } }