CakePHP：如果我在find中组合’fields’和’contains’,我就得不到想要的结果了.有谁能解释为什么？

我有以下情况：作品有一个Image属于ImageGroup.

如果我这样做：

$works = $this->Work->find('all', array(
    'contain' => array(
        'PreviewImage' => array(
            'fields' => array('PreviewImage.id', 'PreviewImage.filename', 'PreviewImage.alt'),
            'ImageGroup' => array(
                'fields' => array('ImageGroup.id')
            )
        )
    )
));

我会得到这个：

array(
(int) 0 => array(
    'Work' => array(
        'id' => '1',
        'title_us' => 'Work Title',
        'title_de' => 'Arbeit Titel',
        'alias' => 'work-title',
        'pdf_id' => '1',
        'date' => '2013-10-08 10:36:00',
        'title_graphic_us_id' => '1',
        'title_graphic_de_id' => '2',
        'body_us' => 'English Content',
        'body_de' => 'Deutscher Inhalt',
        'preview_image_id' => '3',
        'preview_us' => 'English Preview Text',
        'preview_de' => 'Deutscher Vorschau Text',
        'work_layout_id' => '2',
        'state_id' => '1'
    ),
    'PreviewImage' => array(
        'id' => '3',
        'filename' => 'preview_image.png',
        'alt' => 'Preview Image',
        'image_group_id' => '2',
        'ImageGroup' => array(
            'id' => '2'
        )
    )
)

)

但是如果我想通过以下方法减少工作领域：

$works = $this->Work->find('all', array(
    'fields' => array(
        'Work.id'
    ),
    'contain' => array(
        'PreviewImage' => array(
            'fields' => array('PreviewImage.id', 'PreviewImage.filename', 'PreviewImage.alt'),
            'ImageGroup' => array(
                'fields' => array('ImageGroup.id')
            )
        )
    )
));

我突然不再在PreviewImage中获得ImageGroup,请看这里：

array(
(int) 0 => array(
    'Work' => array(
        'id' => '1'
    ),
    'PreviewImage' => array(
        'id' => '3',
        'filename' => 'preview_image.png',
        'alt' => 'Preview Image',
        'image_group_id' => '2'
    )
)

)

我不明白为什么,你有什么想法吗？

解决方法:

我不是100％确定这是否是预期的行为,但您必须在字段配置中包含PreviewImage外键字段才能使其正常工作：

$works = $this->Work->find('all', array(
    'fields' => array(
        'Work.id',
        'Work.preview_image_id'
    ),
    'contain' => array(
        ...
    )
));

文档提到确保在使用包含的fields选项时包含所有必需的外键：

When using ‘fields’ and ‘contain’ options – be careful to include all foreign keys that your query directly or indirectly requires.

http://book.cakephp.org/2.0/en/core-libraries/behaviors/containable.html

所以这可能是功能请求的东西.就个人而言,我本以为这会自动发生.