public function getTree()
        {
            $data = $this->select();
            return $this->_getTree($data);
        }
        /*****递归从数据中找子分类*****/
        private function _getTree($data, $parent_id=0, $level=0)
        {
            static $_ret = array();                
            foreach ($data as $k => $v)
            {
                if($v['parent_id'] == $parent_id)
                {
                    $v['level'] = $level;        //用来标记这个分类是第几级
                    $_ret[] = $v;
                    //找子分类
                    $this->_getTree($data, $v['id'], $level+1);
                }
            }
            return $_ret;
        }

public function edit()
    {
        $id = I('get.id');
        if(IS_POST)
        {
            $model = D('category');
            if($model->create(I('post.'), 2))
            {
                if($model->save() !== FALSE)
                {
                    $this->success('修改成功！', U('lst', array('p' => I('get.p', 1))));
                    exit;
                }
            }
            $this->error($model->getError());
        }    
        
        $model = D('category');
        $data = $model->find($id);
        //取出所有的分类做下拉框
        $catData = $model->getTree();
        //取出当前分类的子分类
        $children = $model->getChildren($id);
        /* var_dump($children);
        var_dump($data);
        var_dump($catData);die(); */
        
        $this->assign(array(
            'children' => $children,
            'data' => $data,
            'catData' => $catData,
            '_page_title' => '修改分类',
            '_page_btn_name' => '分类列表',
            '_page_btn_link' => U('lst'),
        ));
        
        $this->display();
    }

<layout name="layout" />

<div class="main-div">
    <form name="main_form" method="POST" action="__SELF__" >
        <input type="hidden" name="id" value="<?php echo $data['id']; ?>" />
        <table cellspacing="1" cellpadding="3" width="100%">
            <tr>
                <td class="label">上级分类：</td>
                <td>
                    <select name="parent_id">
                        <option value="0">顶级分类</option>
                        <?php foreach($catData as $k => $v):
                            //跳过当前分类和子分类
                            if($v['id'] == $data['id'] || in_array($v['id'], $children))
                                continue;
                            if($v['id'] == $data['parent_id'])
                                $select = 'selected="selected"';
                            else
                                $select = '';
                        ?>
                        <option <?php echo $select; ?> value="<?php echo $v['id']; ?>"><?php echo str_repeat('-', 8*$v['level']) .$v['cat_name']; ?></option>
                        <?php endforeach; ?>
                    </select>
                </td>
            </tr>
            <tr>
                <td class="label">分类名称：</td>
                <td>
                    <input  type="text" name="cat_name" value="<?php echo $data['cat_name'];?>" size='60' />
                </td>
            </tr>
            <tr>
                <td colspan="99" align="center">
                    <input type="submit" class="button" value=" 确定 " />
                    <input type="reset" class="button" value=" 重置 " />
                </td>
            </tr>
        </table>
    </form>
</div>


<script>
</script>