The upload variable is empty in yii2 - yii2

Question

i want add uploadFile to: https://github.com/thyseus/yii2-message
i added public $file2 in Message.php in model
and this is my rules in model:
public function rules()
{
return [
[['title'], 'required'],
[['file2'], 'file', 'skipOnEmpty' => false, 'extensions' => 'png, jpg'],
[['title', 'message', 'context'], 'string'],
[['title'], 'string', 'max' => 255],
[['to'], IgnoreListValidator::class],
[['to'], 'exist',
'targetClass' => Yii::$app->getModule('message')->userModelClass,
'targetAttribute' => 'id',
'message' => Yii::t('app', 'Recipient has not been found'),
],
[['to'], 'required', 'when' => function ($model)
{
return $model->status != Message::STATUS_SIGNATURE && $model->status != Message::STATUS_DRAFT;
}],
];
}
and this is my view:
<?= $form->field($model, 'message')->textarea(['rows' => 6]) ?>
<?php
echo $form->field($model, 'file2')->widget(FileInput::classname(), [
'options' => ['accept' => 'image/*'],
]);
// With model & without ActiveForm
echo '<label class="control-label">Add Attachments</label>';
echo FileInput::widget([
'model' => $model,
'attribute' => 'file2',
'options' => ['multiple' => true]
]);
?>
and this is my sendMessage Function
$model = new Message();
$model->attributes = $attributes;
var_dump($attributes);
die;
why after upload file my result is this?
array(4) { ["to"]=> array(1) { [0]=> string(2) "65" } ["title"]=> string(3) "asd" ["message"]=> string(30) "asd . " ["file2"]=> string(0) "" }
file2 is empty !

Answer 1

When setting up the form, you need to mention as multipart/form-data. check below example.
<?php
use yii\widgets\ActiveForm;
?>
<?php $form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]) ?>
<?= $form->field($model, 'file2')->fileInput() ?>
<button>Submit</button>
<?php ActiveForm::end() ?>