Why is it stored like this in the database?

Question

Yii

there is a Product table with one of the columns tied, it is assumed that related products will be entered there, so its filling is set in the form

<?php 
        $product=Product::find()->where('category_id='.$cat->id)->all();
                foreach($product as $prod){ ?>
                    <?= $form->field($model, 'tied['.$prod->title.']')->checkbox(['value' => $prod->title, 'label' => $prod->title])
                    }
            ?>

here is the part of the action that is responsible for saving to the database

if ($model->load(Yii::$app->request->post())) {
                $post=Yii::$app->request->post();
                foreach($post ["Product"]["tied"] as $tied){
                    $model->tied .=$tied."%";
                }
                $model->save();
           }

But for some reason, the values ​​​​are not overwritten in the database and are added. Do not tell me why and how to deal with it?

Answer 1

I understand that you have one class used i.e. just a product?
If so, then mass work and updates are carried out like this.
In controller:

public function actionUpdate()
    {
        // Тут получаете свой cat либо передаете каким либо образом. 
        $products = Product::find()->where('category_id'= $cat->id)->indexBy('id')->all();

        if (Model::loadMultiple($products, Yii::$app->request->post()) && Model::validateMultiple($products)) {
            foreach ($products as $product) {
                $product->save(false);
            }
            return $this->redirect('index');
        }
        return $this->render('update', ['products' => $products]);
    }

As

$form = ActiveForm::begin();

foreach ($products as $index => $product) {
    echo $form->field($product, "[$index]value")->checkbox(['value' => $prod->title, 'label' => $prod->title]);
}

ActiveForm::end();

If you are using more than one model and related things i.e. like User and Profile, then you need to work with multiple models
. Also, if you are working with relationships, you can use eager loading. loading and linking this way

//получаете продукты и связи за один запрос.
$products = Product::find()->with('category', 'someTied')->all();

//или с условием
$products = Product::find()->with([
    'categpry' => function ($query) {
        $query->andWhere(['category_id' => 15]);
    },
])->all();

If you need to save or update the connected Ids of different objects, there is a link method.