public function getCategory() { return $this->hasOne(Category::className(), ['category_id' => 'category_id'])->viaTable('easyii_article_item_category', ['item_id' => 'item_id'], function ($query) { $query->where('`order`=0'); }); return $this->getItemCategories()->alias('main_category')->on('main_category.order=0'); }