create hiddenfield

_form.php

<?php

use yii\helpers\Html;
use yii\widgets\ActiveForm;

/**
 * @var yii\web\View $this
 * @var common\modules\yii2press\models\BlogCategory $model
 * @var yii\widgets\ActiveForm $form
 */
?>

<div class="blog-category-form">
    <p></p>
	<?php $form = ActiveForm::begin([
        'options' => ['class' => 'form-horizontal'],
        'fieldConfig' => [
            'template' => \common\helpers\ActiveFormHelper::formHorizontalGroupTemplate('col-lg-10'),
            'labelOptions' => ['class' => 'col-lg-2 control-label'],
        ]
    ]); ?>

		<?= $form->field($model, 'name')->textInput(['maxlength' => 255]) ?>

		<?= $form->field($model, 'slug')->textInput(['maxlength' => 255]) ?>

		<?= $form->field($model, 'order')->textInput() ?>

		<?= $form->field($model, 'seo_id',
            [
                'options' => ['class' => ''],
                'template' => '{input}',
            ]
        )->input('hidden') ?>

		<?= $form->field($model, 'theme_id')->textInput() ?>

		<?= $form->field($model, 'post_order')->textInput() ?>

		<div class="form-group">
			<?= Html::submitButton($model->isNewRecord ? 'Create' : 'Update', ['class' => $model->isNewRecord ? 'btn btn-success' : 'btn btn-primary']) ?>
		</div>

	<?php ActiveForm::end(); ?>

</div>