Classify and output instances by level

This article mainly shares with you examples of Thinkphp recursive processing that outputs categories by level. I hope it can help you.

1. Generally, categories are stored in the database, and the relationship between categories is identified by parent_id. In development, sometimes it is necessary to display the classification according to the classification level, as shown below:

Use the recursive method, the source code is as follows:

1. /** 
      *  
      * @param array $list  为一个二维数组，存放着所有的分类，包含的字段为(分类id,分类名,parent_id) 
      * @param number $parent_id 
      * @param number $level 
      * @return Ambigous <multitype:, number> 
      */  
     function find_level($list,$parent_id=0,$level=1){  
         foreach($list as $l){  
             if($l[&#39;parent_id&#39;]==$parent_id){  
                 $l[&#39;level&#39;]=$level;  
                 $arr[]=$l;  
                 $child=$this->find_level($list,$l[&#39;cat_id&#39;],$level+1);  
                 if(is_array($child)){  
                     $arr=array_merge($arr,$child);  
                 }  
             }  
         }  
         return $arr;  
     }

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When using it, just use find_level($list) or $this->find_level($list) according to the actual situation

$list=M('category')->field('cat_id,cat_name,parent_id')->select();  
$list=$this->find_level($list);  
$this->list=$list;  
$this->display();

Front file display code

1. <table>  
   <foreach name="list" item="vo">  
       <tr>  
           <td>  
               <for start="1" end="$vo[&#39;level&#39;]">  
                         
               </for>  
               {$vo.cat_name}<br/>  
           </td>  
       </tr>  
   </foreach>  
   </table>

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The syntax here Using Thinkphp

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