How to set up relationships between models in Yii2?

Question

Yii

The task is executed on Yii2. There are 2 models Book and Author, there are 2 tables in MySQL database book and author. The author stores the id and name of the author. In book, among other things, there is an author_id identifying the author of the book. Through the BookController in the View, all the necessary fields from the book table are displayed in a loop, but besides this, you also need to display the author's name. But since my knowledge of the matbase is below the plinth, I can’t do this. The documentation did not save, by analogy, it was not possible to do 100500 examples found, apparently I'm missing something.
book model:

<?php
namespace app\models;
use yii\db\ActiveRecord;

class Book extends ActiveRecord {
    
    public static function tableName() {
        return 'book';
    }
    
}

Controller BookController:

<?php
namespace app\controllers;
use yii\web\Controller;
use app\models\book;
use app\models\author;

class BookController extends Controller {
        
    public function actionIndex() {
        
        $book = Book::find()->select('image, title')->all();

        $author = 'Тут будет имя автора';
        
        return $this->render('index', compact('book', 'author'));
    }
    
}

Performance:

<div class="col-sm-12 col-md-12">
<?php if(!empty($book)); ?>
<?php foreach($book as $book): ?>
  <div class="col-sm-6 col-md-3 row" style="margin: 20px auto 20px auto;">
    <div class="thumbnail">
      <img src="<?=$book->image?>" alt="...">
      <div class="caption">
        <h3><a href="#"> <?=$book->title?> </a></h3>
        <p> <?=$author ?></p>
      </div>
    </div>
  </div>
<?php endforeach; ?>
</div>
</div>

I give the code without heresy, which I tried to use. Tell me where what and by what methods you need to call to get the name of the author at the output. I’ll just be immensely grateful, I’m already tired of feeling immensely stupid :)

Answer 1

I provided links in my previous reply. Read carefully.
Let's represent the structure book:
id|name|author_id
and present the structure author:
id|name
Let's write two classes:

<?php
class Author extends ActiveRecord
{
    public static function tableName()
    {
       return 'author';
    }

    pubic static function primaryKey()
    {
        return ['id'];
    }
}

class Book extends ActiveRecord
{
    public static function tableName()
    {
       return 'book';
    }

    public static function primaryKey()
    {
        return ['id'];
    }

    public function getAuthor()
    {
        return $this->hasOne(Author::className(), ['id' => 'author_id']);
    }
}

// Использование:
$books = Book::find()->all();
foreach ($books as $book) {
   echo $book->author->name; // сработает метод getAuthor() из Book
}

If you do not understand anything now, then I do not know how to help you)) In the getAuthor() method, we used the hasOne connection.
Read carefully this page:
https://github.com/yiisoft/yii2/blob/master/docs/g...

Answer 2

Did you read the docks ?