如何由用户在数据库中插入主键

Question

我在做cakephp3。在面包店之后，例如用户表，添加动作，在我的项目中，id（primarykey）应由用户填充，蛋糕不会向用户显示id（primarykey）。我使用echo $this->Form->input('id',['type' => 'number']);，但id没有插入数据库。 如何按用户添加主键？

add.ctp

 <?= $this->Form->create($user) ?>
<fieldset>
    <?php
        echo $this->Form->input('id',['type' => 'number']);
        echo $this->Form->input('name');
        echo $this->Form->input('password');
    ?>
</fieldset>
<?= $this->Form->button(__('Submit')) ?>
<?= $this->Form->end() ?>

功能添加（）

public function add() {
    $user = $this->Users->newEntity();
    if ($this->request->is('post')) {
        $user = $this->Users->patchEntity($user, $this->request->data);
        if ($this->Users->save($user)) {
            $this->Flash->success(__('The user has been saved.'));
            return $this->redirect(['action' => 'index']);
        } else {
            $this->Flash->error(__('The user could not be saved. Please, try again.'));
        }
    }
    $roles = $this->Users->Roles->find('list', ['limit' => 200]);
    $dormitories = $this->Users->Dormitories->find('list', ['limit' => 200]);
    $this->set(compact('user', 'roles', 'dormitories'));
    $this->set('_serialize', ['user']);
}