如何在codeigniter中访问数组内部的数组？

Question

我是新来的CI。我有一个功能来访问数据列表作为类别。该功能是这样的：

 public function get_category_tree() 
{ 
    $this->ci->db->where('is_display','1'); 
    $query = $this->ci->db->get('product_categories'); 

    if ($query->num_rows() > 0) 
    { 

     foreach($query->result() as $cat) 
     { 
      if($cat->parent_id=='0'){ 
       //category 
       $categories_arr[$cat->id] = array('id' => $cat->id, 'parent_id'=>$cat->parent_id ,'name' => $cat->name, 'subcat' => ''); 
      }else{ 
       //subcategory; 
       $categories_arr[$cat->parent_id]['subcat'][] = array('id' => $cat->id, 'parent_id' => $cat->parent_id, 'name' => $cat->name); 
      } 
     } 
     return $categories_arr; 
    }    
    return false; 
} 

这个功能是在一般的库中定义的，我访问它从控制器这样的：

$this->data['category_tree'] = $this->general->get_category_tree(); 

而这经常给我这样的结果：

Array 
    (
[id] => 19 
[parent_id] => 0 
[name] => DVDs & Movies 
[subcat] => 
    ) 
    Array 
    (
[id] => 32 
[parent_id] => 0 
[name] => Stamps 
[subcat] => Array 
    (
     [0] => Array 
      (
       [id] => 78 
       [parent_id] => 32 
       [name] => Africa 
      ) 

     [1] => Array 
      (
       [id] => 79 
       [parent_id] => 32 
       [name] => Asia 
      ) 

     [2] => Array 
      (
       [id] => 80 
       [parent_id] => 32 
       [name] => Australia 
      ) 

     [3] => Array 
      (
       [id] => 81 
       [parent_id] => 32 
       [name] => Br Comm Other 
      ) 

     [4] => Array 
      (
       [id] => 82 
       [parent_id] => 32 
       [name] => Canada 
      ) 

     [5] => Array 
      (
       [id] => 83 
       [parent_id] => 32 
       [name] => Europe 
      ) 

     [6] => Array 
      (
       [id] => 84 
       [parent_id] => 32 
       [name] => Latin America 
      ) 

     [7] => Array 
      (
       [id] => 85 
       [parent_id] => 32 
       [name] => Middle East 
      ) 

     [8] => Array 
      (
       [id] => 86 
       [parent_id] => 32 
       [name] => Publications 
      ) 

     [9] => Array 
      (
       [id] => 87 
       [parent_id] => 32 
       [name] => Topical & Specialty 
      ) 

     [10] => Array 
      (
       [id] => 88 
       [parent_id] => 32 
       [name] => UK (Great Britain) 
      ) 

     [11] => Array 
      (
       [id] => 89 
       [parent_id] => 32 
       [name] => United States 
      ) 

     [12] => Array 
      (
       [id] => 90 
       [parent_id] => 32 
       [name] => Worldwide 
      ) 

    ) 

    ) 

现在我升级我的PHP到7+，现在行

$categories_arr[$cat->parent_id]['subcat'][] = array('id' => $cat->id, 'parent_id' => $cat->parent_id, 'name' => $cat->name); 

没有工作，给了PHP的错误，我只是删除[]和它成为

 $categories_arr[$cat->parent_id]['subcat'] = array('id' => $cat->id, 'parent_id' => $cat->parent_id, 'name' => $cat->name); 

现在，当我print_it它给了我这样的结果：

Array 
    (
    [id] => 19 
    [parent_id] => 0 
    [name] => DVDs & Movies 
    [subcat] => 
    ) 
    Array 
    (
    [id] => 32 
    [parent_id] => 0 
[name] => Stamps 
[subcat] => Array 
    (
     [id] => 90 
     [parent_id] => 32 
     [name] => Worldwide 
    ) 

) 

只的最后一个数组子阵列。我该如何解决它。我搜索了很多关于升级和修复的内容，但无法提供任何有用的信息。任何人都可以请帮忙。在此先感谢

Answer 1

因为您定义subcat作为字符串由'subcat' => ''定义$categories_arr[$cat->id]。使用这个：

public function get_category_tree() 
{ 
    $this->ci->db->where('is_display','1'); 
    $query = $this->ci->db->get('product_categories'); 

    if ($query->num_rows() > 0) 
    { 

     foreach($query->result() as $cat) 
     { 
      if($cat->parent_id=='0'){ 
       //category 
       $categories_arr[$cat->id] = array('id' => $cat->id, 'parent_id'=>$cat->parent_id ,'name' => $cat->name, 'subcat' => array()); 
      }else{ 
       //subcategory; 
       $categories_arr[$cat->parent_id]['subcat'][] = array('id' => $cat->id, 'parent_id' => $cat->parent_id, 'name' => $cat->name); 
      } 
     } 
     return $categories_arr; 
    }    
    return false; 
}