A brief introduction to the Infinitus classification tree structure

The following editor will bring you a simple method to create an Infinitus classification tree structure. The editor thinks it’s pretty good, so I’ll share it with you now and give it as a reference. Let’s follow the editor and take a look.

First, let’s take a look at the renderings

##The top category is actually a Second-level classification, second-level classification is also called a sub-category of first-level classification. On this basis, sub-categories can also have sub-categories, thus forming an infinite classification.

Let’s look at the specific implementation code:

1. Query by field in the controller to query all classification information (id: the ID value of the category, cate_name: the name of the category, pid: parent ID, sorts: preparation for displaying the title order, optional.)

public function cate_display()
  {
    $cate = D('Cate'); 
    $field = array('id','cate_name','pid','sorts');
    $list = $cate->allCategory($field);
    $this->assign('list',$list);
    $this->display();
  }

2. Code in the model

Create two methods in the model corresponding to the controller

1. Query all classification information, and Call the method to generate a classification tree:

public function allCategory($field='*'){
     $data = $this->field($field)->select();
     return $this->tree($data);
   }

2. Generate a classification tree (use recursion, pass in data, and pid[parent class id ], level [number of layers, used to control the number of displays] two variables, the initial value is zero)

public function tree($data,$pid=0,$level=0){
    static $tree = array();
    foreach($data as $k=>$v){
      if($v['pid'] == $pid){
        $v['level'] = $level;
        $tree[]=$v;
        $this->tree($data,$v['id'],$level+1);
      }
    }
  
    return $tree;
  }

3. Code in the view file

<p class="form-group">
        <label for="pid" class="col-sm-2 control-label no-padding-right">上级菜单</label>
        <p class="col-sm-6">
          <select name="pid" style="width: 100%;">
            <option selected="selected" value="0">顶级菜单</option>
            <volist name="row" id="val"> 
              <option value="{$val.id}"><?php echo str_repeat(&#39;-&#39;,$val[&#39;level&#39;]*4); ?>{$val.cate_name}
              </option> 
            </volist> 
          </select>
        </p>
      </p>

In this way, a classification tree structure that can be infinitely recursive is completed. Summary: The core idea is still the recursive function in the model, first pass in the pid default is zero. The pid passed in every time in the future is the id of the superior. Level is used to record the number of recursion levels. Finally, when the view page is displayed, the PHP built-in function str_repeat() is called to repeatedly output '-' to reach the output time. Distinguish the effect of progression.

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