public function initialize(array $config): void
{
  parent::initialize($config);

  $this->setTable('users');
  $this->setDisplayField('name');
  $this->setPrimaryKey('id');

  $this->addBehavior('Timestamp');


  //ここから追加
  $this->hasMany('CustomerSender', [
    'className' => 'Reviews',
    'foreignKey' => 'customer_sender_id',
  ]);
  $this->hasMany('ShopReceiver', [
    'className' => 'Reviews',
    'foreignKey' => 'shop_receiver_id',
  ]);   
  //ここまで追加
  
         
}

public function initialize(array $config): void
{
  parent::initialize($config);

  $this->setTable('reviews');
  $this->setDisplayField('id');
  $this->setPrimaryKey('id');

  $this->addBehavior('Timestamp');


  //ここから追加
  $this->belongsTo('Users', [
    'foreignKey' => 'customer_sender_id',
  ]);
  $this->belongsTo('CustomerSender', [
    'className' => 'Users',
    'foreignKey' => 'customer_sender_id',
  ]);
  $this->belongsTo('ShopReceiver', [
    'className' => 'Users',
    'foreignKey' => 'shop_receiver_id',
  ]);
  //ここまで追加
  
  
}

public function add()
{
  $this->loadModel('Users');
        
  $review = $this->Reviews->newEmptyEntity();

  if ($this->request->is('post')) {
    $review = $this->Reviews->patchEntity($review, $this->request->getData());

    if ($this->Reviews->save($review)) {
      $this->Flash->success(__('The review has been saved.'));

      return $this->redirect(['action' => 'index']);
    }else{
      $this->Flash->error(__('The review could not be saved. Please, try again.')); 
    }
  }

  $selectUser = $this->Users->find('list', ['limit' => 100]);

  $this->set(compact('review', 'selectUser'));
}

<?php
/**
 * @var \App\View\AppView $this
 * @var \App\Model\Entity\Review $review
 */
?>
<div class="row">
    <aside class="column">
        <div class="side-nav">
            <h4 class="heading"><?= __('Actions') ?></h4>
            <?= $this->Html->link(__('List Reviews'), ['action' => 'index'], ['class' => 'side-nav-item']) ?>
        </div>
    </aside>
    <div class="column-responsive column-80">
        <div class="reviews form content">
            <?= $this->Form->create($review) ?>
            <fieldset>
                <legend><?= __('Add Review') ?></legend>
                <?php
                    echo $this->Form->control('customer_sender_id', ['options' => $selectUser]);
                    echo $this->Form->control('shop_receiver_id', ['options' => $selectUser]);
                    echo $this->Form->control('message');
                ?>
            </fieldset>
            <?= $this->Form->button(__('Submit')) ?>
            <?= $this->Form->end() ?>
        </div>
    </div>
</div>

public function index()
{
  $reviews = $this->paginate($this->Reviews->find('all', ['contain' => ['Users', 'CustomerSender', 'ShopReceiver']]));

  $this->set(compact('reviews'));
}

<?php
/**
 * @var \App\View\AppView $this
 * @var iterable<\App\Model\Entity\Review> $reviews
 */
?>
<div class="reviews index content">
    <?= $this->Html->link(__('New Review'), ['action' => 'add'], ['class' => 'button float-right']) ?>
    <h3><?= __('Reviews') ?></h3>
    <div class="table-responsive">
        <table>
            <thead>
                <tr>
                    <th><?= $this->Paginator->sort('id') ?></th>
                    <th><?= $this->Paginator->sort('customer_id') ?></th>
                    <th><?= $this->Paginator->sort('shop_id') ?></th>
                    <th><?= $this->Paginator->sort('message') ?></th>
                    <th><?= $this->Paginator->sort('created') ?></th>
                    <th><?= $this->Paginator->sort('modified') ?></th>
                    <th class="actions"><?= __('Actions') ?></th>
                </tr>
            </thead>
            <tbody>
                <?php foreach ($reviews as $review): ?>
                <tr>
                    <td><?= $this->Number->format($review->id) ?></td>
                    <td><?= $review->customer_sender->name ?></td>
                    <td><?= $review->shop_receiver->name ?></td>
                    <td><?= h($review->message) ?></td>
                    <td><?= h($review->created) ?></td>
                    <td><?= h($review->modified) ?></td>
                    <td class="actions">
                        <?= $this->Html->link(__('View'), ['action' => 'view', $review->id]) ?>
                        <?= $this->Html->link(__('Edit'), ['action' => 'edit', $review->id]) ?>
                        <?= $this->Form->postLink(__('Delete'), ['action' => 'delete', $review->id], ['confirm' => __('Are you sure you want to delete # {0}?', $review->id)]) ?>
                    </td>
                </tr>
                <?php endforeach; ?>
            </tbody>
        </table>
    </div>
    <div class="paginator">
        <ul class="pagination">
            <?= $this->Paginator->first('<< ' . __('first')) ?>
            <?= $this->Paginator->prev('< ' . __('previous')) ?>
            <?= $this->Paginator->numbers() ?>
            <?= $this->Paginator->next(__('next') . ' >') ?>
            <?= $this->Paginator->last(__('last') . ' >>') ?>
        </ul>
        <p><?= $this->Paginator->counter(__('Page {{page}} of {{pages}}, showing {{current}} record(s) out of {{count}} total')) ?></p>
    </div>
</div>