relation的用法

以Blog示例：　重点看注释

User类中的relations方法如下

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    <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 ：

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    <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：

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    <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：

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    <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>