关于 PHP 和 MVC 的初学者问题

Question

我正在尝试学习 PHP 的 MVC 架构。所以我玩一些简单的类和函数。我找不到这段代码有什么问题，它返回：

致命错误：在非对象上调用成员函数 fetch() /opt/lampp/htdocs/test/MVC/Vue.php 上 第 15 行

这是我的代码：

Model.php:

class News {
    public function ConnBdd() {
        $this->bdd = new PDO('mysql:host=localhost;dbname=db301591273', 'root', '');
        $this->query = "SELECT Nom,IdTest,Image,DATE_FORMAT(DateCreation, '%Y-%m-%d') AS DateCreation FROM Questionnaires WHERE autorise='1' ORDER BY DateCreation DESC LIMIT 0, 4";
        $this->preparedQuery = $this->bdd->prepare($this->query);
        $this->executedQuery = $this->preparedQuery->execute();
    }
 }

Controller.php

class Controller {
    public $Model;
    public $View;
    public $News;
    public function ShowNews(){
        $this->News->ConnBdd();
        $this->View->ShowDaNews();
    }
}

View.php

class View {
    public $Model;
    public $News;

    public function ShowDaNews() {
        while ($c = $this->News->executedQuery->fetch()) {?>
    <tr>
    <td class="tableImg"><?echo '<img src="/img/ico/'.$tests['Image'].'.png" />'?></td>
    <td class="tableTest"><?echo '<a href="/page/php?t='.$tests['IdTest'].'">'.$tests['Nom'].'</a>'?></td>
    </tr>
            <?}
       }
}

和 Index.php

require_once 'Modele.php';
require_once 'Controleur.php';
require_once 'Vue.php';

$Model= new Model();
$Controller = new Controller();
$View = new View();
$Controller->Model = $Model;
$Controller->View = $View;
$News = new News();
$Controller->News = $News;
$View->News = $News;
$Controller->ShowNews();

感谢您的帮助。

Answer 1

扩展Robin的答案，$stmt->execute()的返回值是一个布尔值，指示语句是否执行成功。

另一方面，如果您正在进行面向对象编程，则应该设置 PDO::ERRMODE 设置，以便在语句失败时抛出异常：

$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

请参阅 http://php.net/manual/en/pdo.setattribute.php

Answer 2

您误解了 PDO 中的准备好的语句，在新闻类中，将其切换为：

$this->preparedQuery = $this->bdd->prepare($this->query);
$this->executedQuery = $this->preparedQuery->execute();

...到此...

$this->preparedQuery = $this->bdd->prepare($this->query);
$this->preparedQuery->execute();
$this->executedQuery = $this->preparedQuery;