简单的activeRecord实现

小弟初学php,在phpchina潜水一段时间受益良多, 现在把自制的activeRecord实现奉上, 有很多拙劣的地方, 希望前辈门能够点评一二
post.model.php

这段代码中把所有的数据存储工作都交给了__get和__set, 这就很糟糕地导致每次sql都只修改一个数据,产生一个页面可能会有上百条sql产生,就像这样...囧:
select title from __posts where id=1
select content from __posts where id=1
select created_at from __posts where id=1
select update_at from __posts where id=1
select title from __posts where id=2
select content from __posts where id=2
select created_at from __posts where id=2
select update_at from __posts where id=2
......
[php]
<?php
## file post.model.php
## <Post> has many <comments>
class Post{

        private $id=0;
        private static $fields = array('title','content','created_at','updated_at');
       
##static
       
        #create a new post object , factory method ?
        #=returns <Post> a post object whick created recently
        static function create($data=array()){
                mysql_query('insert into __posts values ();');
                $result=mysql_query('select id from __posts order by id desc limit 1'); #get the new id
                $post=Post::find(mysql_result($result,0,'id'));
                foreach ($data as $key=>$value){
                                $post->$key=$value;
                }
                return $post;
        }
       
        #find a post
        #=returns <Post> a post object
        static function find($id){
                return new Post($id);
        }
       
        #list posts by page number
        #=returns <Array> , an array of <Post>
        static function list_in_page($page_no,$page_size=10){
                $result=mysql_query("select id from __posts order by created_at desc limit ".(--$page_no)*$page_size.",".$page_size.";");
                $arr=array();
                while($row = mysql_fetch_assoc($result)){
                        $arr[] = self::find($row['id']);
                }
                return $arr;
        }
       
        #list posts which created recently
        #=returns <Array> ,an array of <Post>
        static function list_recent($size=20){
                return self::list_in_page(0,$size);
        }
       
        #list posts
        #=returns <Array> ,an array of <Post>
        static function list_all(){
                $result=mysql_query("select id from __posts order by created_at desc;");
                $arr=array();
                while($row = mysql_fetch_assoc($result)){
                        $arr[] = self::find($row['id']);
                }
                return $arr;
        }
       
        #returns the total number of all posts
        #=returns <Value> , a number
        static function count_all(){
                $result=mysql_query("select count(*) as count from __posts");
                return mysql_result($result,0,'count');
        }
       
##private
       
        #private constructor
        private function Post($id){
                $this->id=$id;
        }
       
##public
       
        #remove this post
        function remove(){
                mysql_query("delete from __posts where id='".$this->id."';");
                mysql_query("delete from __comments where post_id='".$this->id."';");
        }
         
        #setter, set values of this field
        function __set($name,$value){
                if (!in_array($name,self::$fields)) throw new Exception('unkown field');
                mysql_query("update __posts set ".$name." = '".$value."' where id='".$this->id."' ;");
        }
       
        #getter, get the values of this field
        #=returns <value>
        function __get($name){
                if ($name=='id')
                        return $this->id;
                else{
                        $result=mysql_query("select ".$name." from __posts where id='".$this->id."';");
                        return mysql_result($result,0,$name);
                }
        }
       
        #Post has many comments
        #=returns <array> an array of Comment object
        function get_comments(){
                $result=mysql_query("select id from __comments where post_id='".$this->id."' order by created_at");
                $arr=array();
                while($row=mysql_fetch_assoc($result)){
                        $arr[]=Comment::find($row['id']);
                }
               
                return $arr;
        }
       
        #add a comment to this <Post>
        function add_comment($comment){
                $comment->post_id=$this->id;
        }
       
}
?>
[/php]
comments.model.php

<?php
## file comment.model.php
## <Comments> belongs to <Post>
class Comment{

        private $id=0;
        private static $fields=array('post_id','name','content','created_at');
       
##static
       
        #create a new comment object, factory method?
        #=returns <Comment> , a newly created object
        static function create($data=array()){
                mysql_query('insert into __comments values ();');
                $result=mysql_query('select id from __comments order by id desc limit 1'); #get the new id
                $comment=self::find(mysql_result($result,0,'id'));
                foreach ($data as $key=>$value){
                        $comment->$key=$value;
                }
                return $comment;
        }
       
        #find a comment object by id
        #=returns <Comment>
        static function find($id){
                return new Comment($id);
        }
       
##private
       
        #private constructor
        private function Comment($id){
                $this->id=$id;
        }

##public

        #setter, set values of this field
        public function __set($name,$value){
                if (!in_array($name,self::$fields)) throw new Exception('unkown field');
                mysql_query("update __comments set ".$name." = '".$value."' where id='".$this->id."' ;");
        }
       
        #getter, set values of this field
        #=returns <Value>
        public function __get($name){
                if (!in_array($name,self::$fields)) throw new Exception('unkown field');
                if ($name=='id')
                        return $this->id;
                else{
                        $result=mysql_query("select $name from __comments where id='".$this->id."' limit 1;");
                        return mysql_result($result,0,$name);
                }
        }
       
        #remove this comment *but how to destroy this object manually?
        public function remove(){
                mysql_query("delete from __comments where id='".$this->id."';");
        }
       
}
?>

加几个使用实例吧。。。呵呵

:-)

添加post

        $post=Post::create(array(
                'title'=>$title,
                'content'=>$content
        ));


给post添加评论

        $post->add_comment(
                Comment::create(array(
                        'name'=>$name,
                        'content'=>$content
                ))
        );


修改数据(突然想起来貌似忘了写update, 囧):

$post=Post::find($id)
$post->title='test';
$post->content='testtest';


删除post

$Post::find($id)->remove();


枚举post的comments

foreach ($Post::find($id)->get_comments as $c){
     echo '<p>'.$c->name.'</p>'
     echo '<p>'.$c->content.'</p>'
     echo '<p>'.$c->created_at.'</p>'
}

徐希了