如何从MySQL中获取PHP中的对象

Question

我正在尝试生成一个在数据库中提取的对象数组。

我尝试这样做的代码是：

public function findAllObjects() {
    $conn = $this->openConnection();
    $result = $conn->query('SELECT * FROM content');
    while ($content = $result->fetch_object($class = 'Content')) {
        var_dump($content);
        $contents[] = $content;
    }
    $conn = $this->closeConection();
    return $contents;
}

如果我使用var_dump，结果如下：

object(Content)[4]
protected 'id_content' => string '1' (length=1)
public 'title' => null
public 'description' => null
public 'category' => null
public 'date' => string '2015-01-01' (length=10)
public 'townReceiver' => null
public 'author' => null

显然，表Content具有全部信息，但此代码仅获取id和date。有什么解决这个问题的建议吗？非常感谢。

编辑
$class = 'Content'它是参数class_name，来自官方文件：

要实例化的类的名称，设置和的属性回来如果未指定，则返回stdClass对象。

您可以在以下网址找到更多信息：

http://php.net/manual/en/mysqli-result.fetch-object.php
这是class含量的矩阵：

class Content extends Model {
protected $id_content;
public $title;
public $description;
public $category;
public $date;
public $townReceiver;
public $author;
function __construct($title = null, $description = null, $category = null, $townReceiver = null, $author = null) {
    $this->title = $title;
    $this->description = $description;
    $this->category = $category;
    $this->townReceiver = $townReceiver;
    $this->author = $author;
}
//Methods of the class...

编辑2
问题出在__construct方法上。如果我删除此方法，fetch_object可以正常工作原因是什么？我不能将__construct与fetch_object一起使用吗

编辑3
Ryan Vincent评论道，我发现的解决方案是：

function __construct($title = null, $description = null, $category = null, $townReceiver = null, $author = null) {
    if (!isset($this->id_content)) {
        $this->title = $title;
        $this->description = $description;
        $this->category = $category;
        $this->townReceiver = $townReceiver;
        $this->author = $author;
    }
}

Answer 1

最后，问题是对象在调用__construct方法之前被设置，因此，__construct将对象重写为null，正如所定义的那样。

为了避免这种情况，我检查对象的id是否已设置；2种可能性：

1( 如果我想生成一个新内容并将其存储到DB中，那么id将是null，因为id在DB中分配了自动递增选项。

2( 如果我想获取对象，就会设置id，并且数据不会被覆盖。

所以解决方案是这段代码：

function __construct($title = null, $description = null, $category = null, $townReceiver = null, $author = null) {
    if (!isset($this->id_content)) {
        $this->title = $title;
        $this->description = $description;
        $this->category = $category;
        $this->townReceiver = $townReceiver;
        $this->author = $author;
    }
}