Displaying Many to Many result in Yii 2 using GridView?

Question

Yii

1. Three tables are given: Email, Categories, Emailcategories
2. Many to Many relationship is implemented (each email can be in different Categories)
3. Using a getter, I get a multidimensional array that contains a category / categories for each email

public function getItems()
    {
        return $this->hasMany(Categories::className(),['category_id' => 'category_id'])
            ->viaTable('Emailcategories',['email_id' => 'email_id']);
    }

4. As a result, in the GridView, I need to display this in the Categories column (each cell will have at least one category)
Now I can only display the first element:

[
                'attribute' => 'category_id',
                'label' => 'Категория',
                'value' => 'items.0.category',
]

How to parse this items array so that it outputs the corresponding nested element in the corresponding row of the table.

Answer 1

You can pass an anonymous name to value , and in it you can already form the string you want. Like this:

'value' => function($model) {
 return implode(',', $model->items);
}

Answer 2

The function worked:

'value' =>  function($data) {
                    $str ='';
                    foreach($data['items'] as $item)
                    {
                        $str.=$item['category'].',';
                    }
                    return $str;
                },