Yii模型关系加入

Question

1. table Books
2. table Authors
3. table Authors_Category

In Books model have relation:

    public function relations()
    {
        return array(
            'authors' => array(self::BELONGS_TO, 'Authors', array('author_id'=>'id')),
    }

In Authors:

    public function relations()
    {
        return array(
            'authors_category' => array(self::BELONGS_TO, 'Authors_Category', array('author_cat'=>'id')),
    }

In Books DataGridView I can access Authors_Category fields

$data->authors->authors_category->category_name

But problem is in sorting Authors_Category colums

In Books model I have sorting rule:

    return new CActiveDataProvider(
        new FraudAlerts(),
        array(
            'criteria'=>$criteria,
            'sort'=>array(
                'attributes'=>array(
                    'category_name'=>array(
                        'asc'=>'Authors_Category.category_name',
                        'desc'=>'Authors_Category.category_name DESC',
                    ),
                )
            )
        )
    );

When I try sort by Authors_Category fiels I get error, that col category_name not exist.

What is wrong in my relations in Books model ?

Answer 1

As Yatin Mistry pointed out, you have to eager load authors_category for this to work.

Yii allows you to load nested relations using with so this can be accomplished as follows:

$criteria->with = array(
    'authors.authors_category' => array('select' => array('category_name', 'id'))
);

The select limits the fields loaded via the query for improved performance. If you wish to load all the fields from Authors_Category just remove it.