在控件窗体中使用关联数据时，CakePHP 3无法发出标头

Question

我使用的是CakePHP 3.6.7，我的问题是当我在控件窗体中使用关联数据时，我得到了unable to emit headers警告。

下面是我的代码：

AppController.php初始化函数(如果用户已登录，我将从此处检索他的所有数据)

public function initialize() {

parent::initialize();

// Retrieve user data for all views
if($this->request->getSession()->read('Auth.User')) {
    $this->user = $this->Users->get($this->request->getSession()->read('Auth.User.id'), [
        'contain' => ['UserPersonalData']
    ]); 
    $this->set('user', $this->user);
    $this->set('_serialize', 'user');
}

}

UserPersonalDataController.php初始化函数

public function initialize()
{
    parent::initialize();

}

UserPersonalDataController.php编辑功能

public function edit()
{
    if ($this->request->is(['patch', 'post', 'put'])) {
        $userPersonalData = $this->Users->patchEntity($this->user, $this->request->getData());
        if ($this->Users->save($userPersonalData)) {
            $this->Flash->success(__('The user personal data has been saved.'));

            return $this->redirect($this->user->username);
        }
        $this->Flash->error(__('The user personal data could not be saved. Please, try again.'));
    }
}

edit.ctp，下面的窗体将在调试模式下抛出“unable to emit headers”警告

<div class="container" style="padding: 2rem">
<div class="users form large-9 medium-8 columns content">
    <?= $this->Form->create($user, [
        'class' => 'form-signin',
    ]); ?>
    <fieldset>
        <legend><?= __('Edit User') ?></legend>
        <?php
            echo $this->Form->control('user_personal_data.firstName', ['required' => true, 'class' => 'form-control', 'placeholder' => 'First Name', 'label' => false]);
            echo $this->Form->control('user_personal_data.lastName', ['required' => true, 'class' => 'form-control', 'placeholder' => 'Last Name', 'label' => false]);
            echo $this->Form->control('user_personal_data.phone', ['required' => true, 'class' => 'form-control', 'placeholder' => 'Phone', 'label' => false]);
        ?>
    </fieldset>
    <?= $this->Form->button(__('Submit'), ['class' => 'btn btn-lg btn-primary btn-block' ]) ?>
    <?= $this->Form->end() ?>
</div>

​

edit.ctp，则下面的窗体不会抛出任何警告

<div class="container" style="padding: 2rem">
<div class="users form large-9 medium-8 columns content">
    <?= $this->Form->create($user, [
        'class' => 'form-signin',
    ]); ?>
    <fieldset>
        <legend><?= __('Edit User') ?></legend>
        <?php
            echo $this->Form->control('email', ['required' => true, 'class' => 'form-control', 'placeholder' => 'First Name', 'label' => false]);
        ?>
    </fieldset>
    <?= $this->Form->button(__('Submit'), ['class' => 'btn btn-lg btn-primary btn-block' ]) ?>
    <?= $this->Form->end() ?>
</div>

​

正如我所说的，如果我在control() form helper中使用相关数据，它将在调试模式下抛出该警告。如果我不在调试模式下，它会工作得很好，但我担心它。谢谢你的帮助！

编辑:以下是警告的屏幕截图：

​