Find the number of all employees under each department in the department list, and there is a problem of repeated arrays when calling recursively

Question:
The code is as follows:

<code>  //查找所有下级部门的id
    public static function actionSon($company_id,$id)
    {   
        global $temp;
        $modelClass = self::find()
            ->where(['parent_id'=>$id,'company_id'=>$company_id]) 
            ->all();  
        if(!empty($modelClass)){
            foreach ($modelClass as $k => $value) { 
                $temp[] =$value->id;
                self::actionSon($company_id,$value->id);//调用函数，传入参数，继续查询下级
            }
        }
        return $temp;
    }
    </code>

<code>fields里面调用
    public function fields()
    {
        return [
            'id',
            'company_id'
            'user_count'=>function(){

                // return $this->getUserCount();
                $dep_ids=self::actionSon($this->company_id,$this->id);  
                // $GLOBALS['temp']=[];
               //unset($temp);
print_r($dep_ids);
              
            },
        ];
    }</code>

Result output:

Duplicate data is obtained. If there are departments in the list, it will continue to repeat. How to solve this problem?
The result I need is to get the IDs of all sub-departments under the current department every time I call it, and display them in the form of a one-dimensional array.
Release $GLOBALS['temp']=[]; to find only one level.

Reply content:

Question:
The code is as follows:

<code>  //查找所有下级部门的id
    public static function actionSon($company_id,$id)
    {   
        global $temp;
        $modelClass = self::find()
            ->where(['parent_id'=>$id,'company_id'=>$company_id]) 
            ->all();  
        if(!empty($modelClass)){
            foreach ($modelClass as $k => $value) { 
                $temp[] =$value->id;
                self::actionSon($company_id,$value->id);//调用函数，传入参数，继续查询下级
            }
        }
        return $temp;
    }
    </code>

<code>fields里面调用
    public function fields()
    {
        return [
            'id',
            'company_id'
            'user_count'=>function(){

                // return $this->getUserCount();
                $dep_ids=self::actionSon($this->company_id,$this->id);  
                // $GLOBALS['temp']=[];
               //unset($temp);
print_r($dep_ids);
              
            },
        ];
    }</code>

Result output:

Duplicate data is obtained. If there are departments in the list, it will continue to repeat. How to solve this problem?
The result I need is to get the IDs of all sub-departments under the current department every time I call it, and display them in the form of a one-dimensional array.
Release $GLOBALS['temp']=[]; to find only one level.