How to do form validation if you are not using ActiveForm

I can not use ActiveForm widget, but I have form model setup, and I am rendering most of my html using HTML class.

So my view is mixture of HTML wrappers for html fields and plain html because I couldn’t make it work through wrappers.

My question is how to display errors ?

This is the part of my view:


<?php 

$post = Yii::$app->request->post();


foreach ($post as $key => $value) {

  if (!empty($value)) {

    $$key = $value;

  } else {

    $$key = null;

  }

}

?>


<input type="text" value="<?= (isset($searchField) ? $searchField : '') ?>" name="searchField" class="search-fieldEvent" style="background-image: url(images/searchButtonGlobal0.png); background-repeat:no-repeat; 

background-position: 310px 7px; cursor: pointer;"/> 


<?= HTML::dropDownList('eventType', ['value' => (isset($eventType)) ? $eventType : '0'], 

    LookupHelper::eventCategories(), ['class' => 'dropDownL']) ?>


<?= DatePicker::widget([

    'name'  => 'from_date', 

    'value'  => (isset($from_date) ? $from_date : date('d.m.Y')), 

    'language' => Yii::$app->language, 

    'dateFormat' => 'php:d.m.Y',

    'options' => ['class' => 'datepicker-here datePickEvent' , 'id' => 'fromElement']

]); ?>

How can I validate these fields: searchField, eventType and from_date ? Also, as you can see I am trying to keep old values in form after the form is submitted, so user can see what he has typed.

Does anyone have some guide on how to do this a bit better ?