Yii2 获取关系模型的具体属性

Question

我有 2 个模型 Onlinelearning 和 Onlinelearningreviews 有很多关系。我想获取 Onlinelearningreviews 模型的特定属性。

在线学习属性：ID, Title, URL, Description, GradeAge

Onlinelearningreviews 属性：ID, OnlinelearningID, Rating, Comments

模型在线学习：

public function getOnlinelearningreviews()
{
    return $this->hasMany(Onlinelearningreviews::className(), ['OnlineLearningID' => 'ID']);
}

模型在线学习评论：

 public function getOnlineLearning()
 {
        return $this->hasOne(Onlinelearning::className(), ['ID' => 'OnlineLearningID']);
 }

我想要获得 Title, URL, Description, GradeAge and Rating 个属性。

以下作品：

Onlinelearning::find()->select(['Title','URL','Description','GradeAge'])->with('onlinelearningreviews')->asArray()->all();

但是当我指定评级时它给我错误

Onlinelearning::find()->select(['Title','URL','Description','GradeAge','onlinelearningreviews.Rating'])->with('onlinelearningreviews')->asArray()->all();

如何从 Onlinelearningreviews 模型中仅获取 Rating 属性？我不想要其他属性。

Onlinelearning::find()->with(['onlinelearningreviews'])->asArray()->all() 打印：

 Array
    (
        [0] => Array
            (
                [ID] => 1
                [Title] => Udemy
                [URL] => http://www.google.com
                [Description] => Lorem Ipsum is simply dummy text of the printing and typesetting industry.
                [GradeAge] => 2nd to 5th Grade
                [AddedOn] => 2015-03-20 00:00:00
                [LastModifiedOn] => 2015-03-20 00:00:00
                [onlinelearningreviews] => Array
                    (
                        [0] => Array
                            (
                                [ID] => 1
                                [ParentID] => 1
                                [OnlineLearningID] => 1
                                [Rating] => 3.5
                                [PositiveComments] => It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. .
                                [NegativeComments] => 
                                [AddedOn] => 
                                [LastModifiedOn] => 
                            )

                        [1] => Array
                            (
                                [ID] => 2
                                [ParentID] => 1
                                [OnlineLearningID] => 1
                                [Rating] => 3.5
                                [PositiveComments] => It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. 
                                [NegativeComments] => 
                                [AddedOn] => 
                                [LastModifiedOn] => 
                            )

                    )

            )
)

和

Onlinelearning::find()
        ->select(['Title','URL','Description','GradeAge'])
        ->with([
            'onlinelearningreviews' => function ($query) {
                /* @var $query yii\db\ActiveQuery */

                $query->select('Rating');
            },
        ])
        ->asArray()
        ->all();

打印：

Array
(
    [0] => Array
        (
            [Title] => Udemy
            [URL] => http://www.google.com
            [Description] => Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
            [GradeAge] => 2nd to 5th Grade
            [onlinelearningreviews] => Array
                (
                )

        )
)

Answer 1

可能是这样的:

Onlinelearning::find()
    ->select(['Title','URL','Description','GradeAge'])
    ->with([
        'onlinelearningreviews' => function ($query) {
            /* @var $query \yii\db\ActiveQuery */

            $query->select('Rating');
        },
    ])
    ->asArray()
    ->all();

请参阅 official docs，了解如何在 with() 中自定义关系查询。

如果你想 select 来自 Onlinelearning 模型的所有属性你可以省略 select 部分：

->select(['Title','URL','Description','GradeAge'])

更新：

似乎您应该在两个模型中包含连接的属性：

->select(['ID', 'Title','URL','Description','GradeAge'])

和

$query->select(['OnlinelearningID', 'Rating']);

否则会抛出关于Undefinex index的异常

Yii2 获取关系模型的具体属性

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