如何在ngx-tree-select中使用select事件（Angular）

Question

我在我的角度项目中使用ngx-tree-select组件。我对选择事件有疑问。我试图在所选项目发生变化时调用函数，但它不起作用。唯一有效的事件是onModelChange，但它不适合我的情况。也许我做错了什么？请帮帮我）

PHP Warning:  mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given in

在组件中：

 <?php
    include "dbfilepath";
    $con = mysqli_connect($server, $db_user, $db_pwd, $db_name);
    $username = $_SESSION['username'];
    $sql = "SELECT FROM users WHERE username='$username'";
    $data = mysqli_query($con, $sql);
    $row = mysqli_fetch_assoc($data);
    ?>

Answer 1

private _simpleSelected: "any obj";

     get simpleSelected() : any obj {
      return this._simpleSelected;
      }

     set simpleSelected(value: any obj) {
      this._simpleSelected = value;
      }