获取三级以上分类

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当你在数据库中存储了三级以上的数据树时，你想把它显示在前端时，你会怎么做，下面是我在工作项目时遇到的一些思路（此项目是thinkphp5开发的）。

数据库：

demand_id是各分类的ID值，parent_id是用来做树的分类，第一级的parent_id的值是 0 ，第二级的parent_id值是其父级的demand_id值，第三级的parent_id值是其第二级父级的demand_id值，第四、第五同样往后推...

Model:

 //获取三级分类
    public function getTree() {
        $fields = 'demand_id,demand_name,parent_id,sort,status';
        $result = Db::name('demand_class')->field($fields)->where(array('parent_id' => 0, 'status' => 'Y'))->order('parent_id asc, sort asc')->select();
        if (!$result)
            return false;
        $rs = array();
        //顶级不显示图片 ,二级不显示
        foreach ($result as $v) {
            $cate_id = $v['demand_id'];
            $rs[$cate_id]['cate_id'] = $v['demand_id'];
            $rs[$cate_id]['cate_name'] = $v['demand_name'];
            $data = $this->_son_cate($v);

            if ($data) {
                foreach ($data as $key => $val) {
                    // if (!isset($val['child']))
                    // continue; //是否有字分类
//去除二级中图片
                    //unset($val['url']);
                    $rs[$cate_id]['chilid'][] = $val;
                }
            }
        }
        foreach ($rs as $vv) {
            $info[] = $vv;
        }
        return $info;
    }

private function _son_cate($pcate_info) {
        $pcate_id = $pcate_info['demand_id'];
        $fields = 'demand_id,demand_name,parent_id,sort,status';
        $result = Db::name('demand_class')->field($fields)->where(array('parent_id' => $pcate_id))->order('parent_id asc,sort asc')->select();
        if (!$result)
            return false;
        foreach ($result as $v) {
            $cate_id = $v['demand_id'];
            $rs[$cate_id]['cate_id'] = $v['demand_id'];
            $rs[$cate_id]['cate_name'] = $v['demand_name'];

            $data = $this->_son_cate($v);
            if ($data) {
                foreach ($data as $value) {
                    if (!is_file(BASE_UPLOAD_PATH . '/' . ATTACH_COMMON . '/category-pic-' . $value['cate_id'] . '.jpg')) {
                        $value['image'] = PHONE_TEMPLATES . '/' . images . '/' . 'default_goods_image.gif';
                    } else {
                        $value['image'] = UPLOAD_SITE_URL . '/' . ATTACH_COMMON . '/category-pic-' . $value['cate_id'] . '.jpg';
                    }
                    // $value['url']       = htmlspecialchars_decode($value['gc_link']);
                    $rs[$cate_id]['child'][] = $value;
                }
            }
        }
        return $rs;
    }

Contraller:

    public function edit() {
     
        //分类
        $md_goods_class = Model('demand_class');
        $denamd_class = $md_goods_class->getTree();
        $this->assign('denamd_class', $denamd_class);
        return $this->fetch('demand_from');
    }

前端 demand_from.html

 <select id='ac_id' name="ac_id">
                        <option value="">点击选择发布类别</option> 
                        <?php $ac_id=$output['list']['ac_id']; if(!empty($output['denamd_class'])&&is_array($output['denamd_class'])){?>
                        <?php foreach($output['denamd_class'] as $val){?>
                        <option value="<?php echo $val['cate_id']?>"<?php if($val['cate_id']==$ac_id){echo 'selected="selected"';}?> ><?php echo $val['cate_name'] ?></option>
                        <?php if(!empty($val['chilid'])&&is_array($val['chilid'])){?>
                        <?php foreach($val['chilid'] as $v1){?>
                        <option  value="<?php echo $v1['cate_id']?>" <?php if($v1['cate_id']==$ac_id){echo 'selected="selected"';}?>>&nbsp;&nbsp;<?php echo $v1['cate_name'] ?></option>
                        <?php if(!empty($v1['child'])&&is_array($v1['child'])){?>
                        <?php foreach($v1['child'] as $v2){?>
                        <option  value="<?php echo $v2['cate_id']?>" <?php if($v2['cate_id']==$ac_id){echo 'selected="selected"';}?>>&nbsp;&nbsp;&nbsp;&nbsp;<?php echo $v2['cate_name'] ?></option>
                        <?php }?>
                        <?php }?>
                        <?php }?>
                        <?php }?>
                        <?php }?>
                        <?php }?>
                    </select>

我之前遇到的问题：

当我在前端看的时候发现cate_id 这个字段，我去它的控制器中查找，找到了它使用的demand_class数据表，然后去数据表里看发现表里并没有这个字段，通过我认真的查找我发现这个字段是从模型Model中定义来的。

注：文章来源雨中笑记录实习期遇到的问题与心得，转载请申明原文