yii2：如何在一个数组变量中使用多核对表值

Question

Code from _formCreate.php

<div class="col-lg-6 height3">
  <p  class="col-lg-8">ورزشی</p>
    <?= $form->field($model, 'project_control_id[]')->input('checkbox', [ 'value' => '1', 'class' => 'col-lg-4'])->label('') ?>
</div>

<div class="col-lg-6 height3">
  <p class="col-lg-8">سرگرمی</p>
    <?= $form->field($model, 'project_control_id[]')->input('checkbox', [ 'value' => '2', 'class' => 'col-lg-4'])->label('') ?>
</div>

Model variable:

public $project_control_id;

Defined rules(){ [['project_control_id'], 'string', 'max' => 5000],

My $model is not saved when I call:

<?= $form->field($model, 'project_control_id[]')->input

but is saved properly in this case:

<?= $form->field($model, 'project_control_id')->input

The question is why my model is not saved in the first case?