为什么json_encode返回空括号？

Question

的var_dump $阵列的返回这样的：

array (size=3) 
    0 => 
    object(frontend\models\Notifications)[101] 
     private '_attributes' (yii\db\BaseActiveRecord) => 
     array (size=5) 
      'id' => int 1 
      'created_on' => string '2015-11-12 12:12:15' (length=19) 
      'user_id' => int 1 
      'text' => string '2severity level is 2guardian is 5,Student_id 2 created a Level 2 discipline issue in school' (length=91) 
      'is_seen' => int 0 
     private '_oldAttributes' (yii\db\BaseActiveRecord) => 
     array (size=5) 
      'id' => int 1 
      'created_on' => string '2015-11-12 12:12:15' (length=19) 
      'user_id' => int 1 
      'text' => string '2severity level is 2guardian is 5,Student_id 2 created a Level 2 discipline issue in school' (length=91) 
      'is_seen' => int 0 
     private '_related' (yii\db\BaseActiveRecord) => 
     array (size=0) 
      empty 
     private '_errors' (yii\base\Model) => null 
     private '_validators' (yii\base\Model) => null 
     private '_scenario' (yii\base\Model) => string 'default' (length=7) 
     private '_events' (yii\base\Component) => 
     array (size=0) 
      empty 
     private '_behaviors' (yii\base\Component) => 
     array (size=0) 
      empty 
    1 => 
    object(frontend\models\Notifications)[108] 
     private '_attributes' (yii\db\BaseActiveRecord) => 
     array (size=5) 
      'id' => int 2 
      'created_on' => string '2015-11-12 12:12:15' (length=19) 
      'user_id' => int 1 
      'text' => string '2severity level is 2guardian is 5,Student_id 2 created a Level 2 discipline issue in school' (length=91) 
      'is_seen' => int 0 
    ................................ 
    ................................ 
    ................................ 

但json_encode（$阵列）返回[{}，{}，{}]。 我试图： 试图改变整个数据库的字符编码为utf8_general_ci。

对于我的表，字符编码是utf8_general_ci，因此对于表的“文本”列。可能是什么问题？

Answer 1

您显示的数组的所有属性都是私有的。这意味着这个值在其课程范围之外是不可用的。

你可以看看这个SO一些建议

Using json_encode on objects in PHP (regardless of scope)