CakePHP：几个连接，belongsTo和hasMany关系在两个查询中完成

时间：2012-12-17 19:51:29

标签： php mysql cakephp has-many belongs-to

我需要一些CakePHP 2.2.3的帮助。

我拥有什么

我现在有以下设置：

Post hasMany Attachment

它工作正常，页面生成2个查询：

SELECT *, `Post`.`id` 
FROM `posts` AS `Post` 
WHERE 1 = 1 
ORDER BY `Post`.`created` DESC

SELECT 
    `Attachment`.`id`, 
    `Attachment`.`post_id`, 
    `Attachment`.`created` 
FROM 
    `attachments` AS `Attachment` 
WHERE 
    `Attachment`.`post_id` IN (1, 2, 3, ..., n)

我想要什么

我想将关系扩展如下：

Post hasMany Attachment;每个Attachment 属于 Type

我不太热衷于让CakePHP遵循它 基本上，我需要的是：

SELECT *, `Post`.`id` 
FROM `posts` AS `Post` 
WHERE 1 = 1 
ORDER BY `Post`.`created` DESC

SELECT 
    `Attachment`.`id`, 
    `Attachment`.`post_id`, 
    `Attachment`.`created`, 
    `Type`.`title`, `Type`.`icon` 
FROM 
    `attachments` AS `Attachment` 
LEFT JOIN 
    `types` AS `Type` 
    ON (`Attachment`.`type_id`=`Type`.`id`) 
WHERE 
    `Attachment`.`post_id` IN (1, 2, 3, ..., n)

注意添加了LEFT JOIN types。

所以我在第二个查询中得到了相应的类型数据。我知道我可以循环获取数据或使用->query()调用，但我希望它尽可能有效和灵活。

问题

我尝试了Containable，Model Unbinding trick（and this one）但没有成功。我尝试了不同的选项组合，我相信我甚至删除了连接。这就是我PostsController现在的样子。

class PostsController extends AppController {
    public function index() {

        $this->Post->unbindModel(array('hasMany' => array('Attachment')));
        $this->Post->Attachment->unbindModel(array('belongsTo' => array('Type')));

        $this->Post->bindModel(array(
            'hasMany' => array(
                'Attachment' => array(
                    'className'  => 'Attachment',
                // when uncommented, throws the "Unknown column Post.id" SQLSTATE error
                //  'conditions' => array('Post.id' => 'Attachment.post_id'),
                    'foreignKey' => false,
                ),
            ),
        ));
        $this->Post->Attachment->bindModel(array(
            'belongsTo' => array(
                'Filetype' => array(
                    'className'  => 'Filetype',
                //  'conditions' => array('Type.id' => 'Attachment.type_id'),
                    'foreignKey' => false,
                ),
            ),
        ));
        $all = $this->Post->find('all', array(
            'joins' => array(
                array(
                    'table' => 'users',
                    'prefix' => '',
                    'alias' => 'User',
                    'type' => 'INNER',
                    'conditions' => array(
                        'User.id = Post.user_id',
                    )
                ),
            ),
            'contain' => array('Attachment', 'Type'),
            'conditions' => array(),
            'fields' => array('*'),
            'order' => 'Post.created ASC'
        ));
        var_dump($all);exit;
    }
}

但它只是在循环中每次迭代运行一个额外的查询，并获得 all 附件：

SELECT `Attachment`.`id`, ... 
FROM `attachments` AS `Attachment` 
WHERE 1 = 1

当我取消注释这个关联的条件时，它会抛出SQLSTATE“Column Post.id not found error” - 我猜是因为这里没有Post表加入。

我需要一手设置。

请帮忙！感谢

更新

我按如下方式更改了控制器。请注意，没有bindModel / unbindModel代码，关系是在模型类中设置的（在这种情况下是正确的吗？）。

class PostsController extends AppController {
    public function index() {
        $options = array(
            'contain' => array(
                'Post',
                'Type'
            ),
            'order' => 'Post.created DESC',
            'conditions' => array(
            //  'Post.title LIKE' => 'my post'
            )
        );

    //  The following throws "Fatal error: Call to a member function find() on a non-object"
    //  $posts = $this->Attachment->find('all', $options); 

    //  So I had to use $this->Post->Attachment instead of $this->Attachment
        $posts = $this->Post->Attachment->find('all', $options);
        $this->set(compact('posts'));
    }   
}

这是Attachment型号：

class Attachment extends AppModel {
    public $belongsTo = array(
        'Type' => array(
            'className' => 'Type',
            'foreignKey' => 'type_id',
        ),
        'Post' => array(
            'className' => 'Post',
            'foreignKey' => 'post_id',
        ),
    );
}

以上代码运行此查询：

SELECT 
    `Attachment`.`id`, `Attachment`.`type_id`, `Attachment`.`post_id`, `Attachment`.`created`, 
    `Type`.`id`, `Type`.`title`, 
    `Post`.`id`, `Post`.`text`, `Post`.`created` 
FROM 
    `attachments` AS `Attachment` 
    LEFT JOIN `types` AS `Type` ON (`Attachment`.`type_id` = `Type`.`id`) 
    LEFT JOIN `posts` AS `Post` ON (`Attachment`.`post_id` = `Post`.`id`) 
WHERE 
    1 = 1 
ORDER BY 
    `Post`.`created` ASC

这里的一切都是关于附件的。我的意思是帖子已加入附件，因此如果帖子没有附件，则不会返回。这可能是因为呼叫是Attachment->find()所以它来自附件的观点。我想它应该是：

// ...
FROM 
    `posts` AS `Post`
    LEFT JOIN `attachments` AS `Attachment`  ON (`Attachment`.`post_id` = `Post`.`id`) 
    LEFT JOIN `types` AS `Type` ON (`Attachment`.`type_id` = `Type`.`id`) 
// ...

但它不会起作用，是吗？您会看到posts，attachments和types，但它们确实具有不同的关系类型。最初，我发布了CakePHP运行的两个单独的查询 - 必须有原因。

UPDATE2

我仍然相信在初始设置中将第二个查询更改为Attachment模式（请参阅我想要的内容部分）。所以我将获得附件类型以及附件本身。我的意思是在那种情况下，将types表连接到attachments并不会破坏任何数据库关系逻辑，是吗？ 我只是想确保通过一个复杂但单find()次呼叫无法做到这一点。

2 个答案:

答案 0 :(得分：3)

每当Cake看到hasMany关系时，它都会自动创建多个查询以提取数据。在构造这些查询时，它会查找可以左键连接到它的关系（hasOne和belongsTo）。

由于Cake无法为您执行此操作，因此您需要自己合并它们。

public function index() {
  $posts = $this->Post->find('all');
  // get all attachments for all found posts
  $attachments = $this->Post->Attachment->find('all', array(
    'contain' => array('Type'),
    'conditions' => array('Post.id' => Set::extract('/Post/id', $posts)
  ));
  // now join them to the posts array
  foreach ($posts as $key => $data) {
    $postId = $data['Post']['id'];
    // append any data related to this post to the post's array
    $posts[$key] += Set::extract("/Attachment[post_id=$postId]/..", $attachments);
  }
  $this->set(compact('posts'));
}

这不是最有效的方法，因为你会多次遍历$attachments数组，但我相信你明白了。

答案 1 :(得分：0)

在hasMany中尝试finderQuery。 例如： 在Post模型中，

public $hasMany = array(
    'Attachment' => array(
        'className' => 'Attachment',
        'foreignKey' => 'post_id',
        'dependent' => false,
        'conditions' => '',
        'fields' => '',
        'order' => '',
        'limit' => '',
        'offset' => '',
        'exclusive' => '',
        'finderQuery' => '                            
             SELECT 
                 `Attachment`.`id`, 
                 `Attachment`.`post_id`, 
                 `Attachment`.`created`, 
                 `Type`.`title`, 
                 `Type`.`icon` 
                  FROM 
                 `attachments` AS `Attachment` 
                  LEFT JOIN 
                 `types` AS `Type` 
                  ON (`Attachment`.`type_id`=`Type`.`id`) 
                   WHERE 
                          `Attachment`.`post_id` IN (1, 2, 3, ..., n)
                ',
        'counterQuery' => ''
    )
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