$this->value 损失，嗯，它的价值 [英] $this->value losing, well, its value

问题描述

我使用的 PHP 文件有问题，我似乎找不到解决方案.

I have a problem with a PHP file I'm using, and I can't seem to find a solution.

在代码的一部分中，设置了 $this->value 的值，并且根据我的测试正确设置了该值.

In one part of the code the value for $this->value is set, and the value is set correctly according to my testing.

然而，在相同的代码中，$this->value 为空.

However, later in the same code $this->value is empty.

代码如下:

<?php

class Padd_Input_Advertisement {

    protected $keyword;
    protected $value;
    protected $name;
    protected $description;

    function __construct($keyword,$name,$description='') {
        $this->keyword = $keyword;
        $this->value = unserialize(get_option($keyword));
        $this->name = $name;
        $this->description = $description;
    }

    public function get_keyword() {
        return $this->keyword;
    }

    public function set_keyword($keyword) {
        $this->keyword = $keyword;
    }

    public function get_value() {
        return $this->value;
    }

    public function set_value($value) {
        $this->value = $value;
    }

    public function get_name() {
        return $this->name;
    }

    public function set_name($name) {
        $this->name = $name;
    }

    public function get_description() {
        return $this->description;
    }

    public function set_description($description) {
        $this->description = $description;
    }

    public function  __toString() {

        $strHTML  = '';
        $strHTML .= '<tr valign="top">';
        $strHTML .= '   <th scope="row"><label for="' . $this->keyword . '">' . $this->name . '</label></th>';
        $strHTML .= '   <td>';
        $strHTML .= '       <label for="' . $this->keyword. '_alt_desc">Short Description</label><br />';
        $strHTML .= '       <input name="' . $this->keyword . '_alt_desc" type="text" id="' . $this->keyword . '_alt_desc" value="' . $this->value->get_alt_desc() . '" size="80" /><br />';
        $strHTML .= '       <label for="' . $this->keyword. '_img_url">Image URL</label><br />';
        $strHTML .= '       <input name="' . $this->keyword . '_img_url" type="text" id="' . $this->keyword . '_img_url" value="' . $this->value->get_img_url() . '" size="80" /><br />';
        $strHTML .= '       <label for="' . $this->keyword. '_web_url">Website</label><br />';
        $strHTML .= '       <input name="' . $this->keyword . '_web_url" type="text" id="' . $this->keyword . '_web_url" value="' . $this->value->get_web_url() . '" size="80" />';
        $strHTML .= '       <br /><small>' . $this->description . '</small>';
        $strHTML .= '   </td>';
        $strHTML .= '</tr>';
        return $strHTML;
    }

}

?>

在 function __construct 的顶部，设置了值，我确认发生了这种情况.

At the top in function __construct, the value is set, and I confirmed that this happens.

然而，在底层函数function __toString中，$this->value为空.

However, in the bottom function function __toString, $this->value is blank.

知道是什么原因造成的吗?

Any idea what could be causing this?

编辑

所以，总结一下，$this->value 在 __construct 函数中设置正确，但在 __toString 函数中为空.

So, to recap, $this->value is set properly in the __construct function, but is blank in the __toString function.

编辑 2

我还应该提到在 __construct 函数中设置的其他变量也在 __toString 函数中起作用，例如 $this->keyword.只是 $this->value 变成空白.

I should also mention that other variables that are set in the __construct function are working in the __toString function, like $this->keyword. It's jut $this->value that is going blank.

编辑 3这个类是这样调用的

$padd_options['advertisements'] = array(
    new Padd_Input_Advertisement(
        PADD_NAME_SPACE . '_ads_125125_1',
        'Square Ad 1 (125x125)',
        'The advertisement will be posted at the side bar.'
    ),
    new Padd_Input_Advertisement(
        PADD_NAME_SPACE . '_ads_125125_2',
        'Square Ad 2 (125x125)',
        'The advertisement will be posted at the side bar.'
    ),
    new Padd_Input_Advertisement(
        PADD_NAME_SPACE . '_ads_125125_3',
        'Square Ad 3 (125x125)',
        'The advertisement will be posted at the side bar.'
    ),
    new Padd_Input_Advertisement(
        PADD_NAME_SPACE . '_ads_125125_4',
        'Square Ad 4 (125x125)',
        'The advertisement will be posted at the side bar.'
    ),
);

推荐答案

这是因为未序列化的对象在不知道类的类型时不保留方法.

It's because unserialized object does not keep methods if they do not know the type of the class.

当您对 get_keyword() 函数调用的结果进行反序列化时，如果序列化对象的类未知，PHP 将回退到特殊类 __PHP_Incomplete_Class_Name.这个类基本上是一个虚拟类:它没有任何方法.但是，它允许您访问反序列化对象的属性.

When you unserialize the result of the get_keyword() function call, if the class of the serialized object is not known, PHP will fallback on the special class __PHP_Incomplete_Class_Name. This class is basically a dummy class : it doesn't have any method. However, it allows you to access to the attributes of the deserialized object.

因此，如果您希望能够调用 $this->value 的方法(这就是您在 __toString 中所做的)，您将有在调用反序列化之前包含声明 $this->value 类型的文件.

So, if you want to be able to call the method of $this->value (which is what you are doing in __toString), you will have to include the file which declares the type of $this->value before calling unserialize.

[edit] 您可以查看 PHP 手册 有关反序列化过程的更多详细信息.

[edit] You can check the PHP manual for more details about the unserialization process.

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