是否存在与PDO :: FETCH_CLASS相反的内容或将对象映射回数据库中 [英] Does the contrary of PDO::FETCH_CLASS exists or mapping an object back in the database

问题描述

使用PDO，我们现在可以以惊人的速度轻松地将字段映射到对象的属性.这个:

With PDO, we can now easily map our fields to an object's property, at a blazing speed. this:

class myClass
 {}
$stmt = $db->prepare('SELECT foo,bar FROM table WHERE id=28');
$stmt->setFecthMode(PDO::FETCH_CLASS,'myClass');
$object = $stmt->fetch();

$object现在是myClass类的对象，具有foo和bar作为属性.整洁！

$object is now an object of class myClass with foo and bar as properties. neat!

现在，如果我可以仅使用PDO或php甚至MySQL的内置函数将对象保存回数据库中，那岂不是令人难以置信！像这样的东西:

Now, wouldn't it be incredible if I could save my object back in the database just with built-in functions from PDO or php, or even MySQL! something like this:

$stmt = $db->prepare('UPDATE table SET * = ?');
$stmt->setUpdateMode(PDO::UPDATE_CLASS);
$stmt->execute($object);

到目前为止，我为每个实例定义了自定义保存类.虽然速度很快，但维护起来很麻烦，而且容易出错.

As of now, I define custom saving classes for each instance. While fast, this is a hassle for maintaining and very error-prone.

当然，对象必须具有与其尝试更新的属性完全相同的属性，或者可以包含更少的字段，但不能更多.

Of course, an object must have exactly the same properties as what it's trying to update, or maybe less fields, but not more.

它存在吗?缺少PDO作为完美的ORM吗?！

推荐答案

所以我最终使用了oop的一个非常突出的功能:析构函数！

So I ended up using a very prominent feature of oop: destructors!

一旦没有其他对特定对象的引用，或者在关闭序列期间以任何顺序进行调用，则析构函数方法将被调用.

The destructor method will be called as soon as there are no other references to a particular object, or in any order during the shutdown sequence.

来自 http://php.net/manual/en/language.oop5 .decon.php

这很贴心，因为我想要的是在两次点击之间保持对象的状态.这意味着不同的事物，我不确定它们是否是好的做法，但这有点容易出错.

which is very sweet, because what I want is to maintain the state of my objects between clicks on my website. This implies different things which I am not sure if they are good practice or not, but it is a bit error prone.

• 数据库中的字段和对象属性应该相同，以简化析构函数代码并使其更易于移植
• 我正在使用PDO的FETCH_CLASS模式来构建对象(如在问题中一样)

• The fields in the database and the object properties should be the same to simplify destructor code and make it more portable
• I'm using PDO's FETCH_CLASS mode to build an object (as in the question)

现在有趣的部分是析构函数，它可以将属性保存回数据库中的相关字段:

now the interesting part is with the destructor, which can save back the properties to the relevant fields in the database:

function __destruct()
 {
  $whitelist = array_flip(array('foo','bar'));
  // I'm pretty sure not all my properties belong in my table
  foreach (get_object_vars($this) as $key => $value)
   {
    if (!isset($whitelist[$key])) continue;
    $fields[] = $key . '=?';
    $values[] = $value; 
    }
  $sql = 'UPDATE table SET ' . implode($fields) . 'WHERE id=?';
  $values[] = $this->getId();
  $stmt = $db->prepare($sql);
  $stmt->execute($values);
  }

就在那里！下次我从数据库构造对象时，它与上次访问时完全相同.

and there it is! next time I construct my object from the database, it is exactly the same as it was the last time it was accessed.

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