Yii中的relations方法

以Blog示例：　重点看注释

User类中的relations方法如下 

<span style="font-size:18px;background-color: rgb(255, 255, 255);"> public function relations()
    {
        return array(
            'posts' => array(self::HAS_MANY, 'Post', 'author_id',
                'order'=>'posts.update_time DESC',
                'with'=>'comments:approved',  // $user = User::model()->findByPk(1); 这里也查出了每篇post所带的comments
                //approved是comment的命名空间，可以在这里设置
                //'together'=>false,  设置这一项，关联查新将被分为几个SQL语句执行，和性能有关系
            ),
            'postCount'=>array(
                self::STAT,'Post','author_id',
                'condition'=>'status='.Post::STATUS_PUBLISHED,
            ),
        );
    }</span>

Post中的方法如下 ： 

<span style="font-size:18px;background-color: rgb(255, 255, 255);">public function relations()
    {
        // NOTE: you may need to adjust the relation name and the related
        // class name for the relations automatically generated below.
        return array(
            'author'=>array(self::BELONGS_TO,'User','author_id',
                //'select'=>'id,username,profile',    // 关联查询的选项，如果不设置，则默认为*即整个关联记录
            ),
            'comments'=>array(self::HAS_MANY,'Comment','post_id',
            'condition'=>'comments.status='.Comment::STATUS_APPROVED,
            'order'=>'comments.create_time DESC'),
            'commentCount'=>array(
                self::STAT,'Comment','post_id',
                'condition'=>'status='.Comment::STATUS_APPROVED
            ),
        );
    }
</span>

Comment中的ralations方法如下：

<span style="font-size:18px;background-color: rgb(255, 255, 255);">public function attributeLabels()    //名字和现实标签的映射数组
    {
        return array(
            'id' => 'Id',
            'content' => 'Comment',
            'status' => 'Status',
            'create_time' => 'Create Time',
            'author' => 'Name',
            'email' => 'Email',
            'url' => 'Website',
            'post_id' => 'PostID',   //对应的博客ID
        );
    }
</span>

在控制器中写个方法测试一下结果：

<span style="font-size:18px;background-color: rgb(255, 255, 255);"> public function actionRQ(){
        $post = Post::model()->find('id=:id',array(':id'=>7));
        echo $post->author->username;

        echo "<hr>";
        $posts = Post::model()->with('author','comments')->findAll();   //急切加载
        foreach($posts as $post){
            echo $post->id."  |";
            foreach($post->comments as $comment){
                echo $comment->id.": ";
                echo $comment->content."<br>";
            }
            echo $post->author->username."<br>";
        }
        echo "<hr>";
        $user = User::model()->with('posts.comments')->findByPk(1);
        //$user = User::model()->findByPk(1);  这一句和上一句是一样的，因为在User的relations声明的posts也已经加上了关联查询：with=>'comments'
        foreach($user->posts as $post){    //嵌套急切加载
            echo $post->title." (";
            foreach($post->comments as $comment){
                echo $comment->id." : ";
                echo $comment->content."<br>";
            }
            echo ")".$post->tags."<br>";
        }

        echo "<hr>";
        $criteria = new CDbCriteria;
        //$criteria->select = "username";
        //$criteria->order
        //$criteria->limit
        //$criteria->condition
        //$criteria->params
        $criteria->with = array(
            'posts.comments',
        );
        $users = User::model()->findAll($criteria);
        foreach($users as $user){
            echo $user->username.":<br>";
            //echo $user->password;
            foreach($user->posts as $post){    //嵌套急切加载
                echo $post->title." (";
                foreach($post->comments as $comment){
                    echo $comment->id." : ";
                    echo $comment->content."<br>";
                }
                echo ")".$post->tags."<br>";
            }
        }

        //动态关联查询，也就是在查询的时候覆盖relations中设置的关联的选项
        echo "<hr>";
        $user=User::model()->with(array(
            'posts'=>array(
                'order'=>'posts.update_time DESC',
                'with'=>array('comments'=>array('order'=>'comments.id ASC')),
                //'together'=>false,   //关联声明中设置together 选项为false 以便一些表被连接在单独的SQL语句中,分为几个SQL语句执行
            ),
        ))->findByPk(1);
        echo "demo 的posts数量为：".$user->postCount;
        echo "<br>";
        foreach($user->posts as $post){
        echo $post->id."(";
            echo $post->title."的评论数量是：".$post->commentCount."<br>";
            foreach($post->comments as $comment){
                echo $comment->id." | ";
            }
            echo ")";
            echo "<br>";
        }
    }</span>
原文来自 http://blog.csdn.net/littlebearwmx/article/details/8561018