Yii2. 找不到数据库写入错误的原因

我无法将数据写入表，我收到错误：

SQLSTATE[HY000]: General error: 1364 Field 'user_id' doesn't have a default value
The SQL being executed was: INSERT INTO `contact` (`id`) VALUES (DEFAULT)
Error Info: Array
(
    [0] => HY000
    [1] => 1364
    [2] => Field 'user_id' doesn't have a default value
)

控制器：

$model = new ContactForm();
$model->id = 0;
$model->user_id = Yii::$app->user->id;
$model->save(false);

模型（禁用验证规则）：

class ContactForm extends \yii\db\ActiveRecord
{
  public $id;
  public $user_id;
  //...
}

var_dump：

object(app\models\ContactForm)#214 (12) { ["id"]=> int(0) ["user_id"]=> int(4) ["_attributes":"yii\db\BaseActiveRecord":private]=> array(0) { } ["_oldAttributes":"yii\db\BaseActiveRecord":private]=> NULL ["_related":"yii\db\BaseActiveRecord":private]=> array(0) { } ["_relationsDependencies":"yii\db\BaseActiveRecord":private]=> array(0) { } ["_errors":"yii\base\Model":private]=> NULL ["_validators":"yii\base\Model":private]=> NULL ["_scenario":"yii\base\Model":private]=> string(7) "default" ["_events":"yii\base\Component":private]=> array(0) { } ["_eventWildcards":"yii\base\Component":private]=> array(0) { } ["_behaviors":"yii\base\Component":private]=> array(0) { } }

表格：用户和联系表格

$this->createTable('user', [
  'id' => $this->primaryKey(),
  //...
], $tableOptions);

和

$this->createTable('{{%contact}}', [
  'id' => $this->primaryKey(),
  'user_id' => $this->integer(11)->notNull(),
  //...
], $tableOptions);


$this->createIndex(
  'idx-contact-user_id',
  'contact',
  'user_id'
);


$this->addForeignKey(
  'fk-contact-user_id',
  'contact',
  'user_id',
  'user',
  'id',
  'CASCADE'
);

在这种情况下，手动通过phpMyAdmin进行输入。

问题的原因可能是什么？