设置一个PHP对象全局？ [英] Set a PHP object global?

问题描述

我刚开始将我的项目从mysql切换到PDO。在我的项目中，一个新的PDO对象在程序的开始时或多或少地被创建。

  $ dbh_pdo = new PDO（mysql：host = $ db_url; dbname = $ db_database_name，$ db_user，$ db_password） ; 
  

现在我想在一些函数和类中使用这个处理程序（是正确的名称吗？ 。有没有办法使对象全局变量像变量一样，或者我尝试了一些无法理解的愚蠢的东西，因为在搜索网页时我找不到任何东西...

解决方案

是的，您可以像对待任何其他变量一样使对象成为全局对象：

  $ pdo = new PDO （ '东西'）; 
函数foo（）{
 global $ pdo; 
 $ pdo-> prepare（'...'）; 
} 
  

您可能还想查看Singleton模式，它基本上是全局，OO风格。

这就是说，我建议你不要使用全局变量。在调试和测试时，它们可能会很痛苦，因为很难分辨修改/使用/访问它是因为什么都可以。他们的用法一般被认为是不好的做法。考虑仔细检查一下你的设计。

我不知道你的应用程序是怎么样的，但是说你是这样做的：

  class TableCreator {
 public function createFromId（$ id）{
 global $ pdo; 
 $ stmt = $ pdo-> prepare（'SELECT * FROM mytable WHERE id =？'）; 
 $ stmt-> execute（array（$ id））; 
 $ rows = $ stmt-> fetchAll（PDO :: FETCH_ASSOC）; 
 foreach（$ rows as $ row）{
 // do stuff 
} 
} 
} 
  

您应该这样做：

  class TableCreator {
 protected $ pdo; 
 
 public function __construct（PDO $ pdo）{
 $ this-> pdo = $ pdo; 
 
 
 public function createFromId（$ id）{
 $ stmt = $ this-> pdo-> prepare（'SELECT * FROM mytable WHERE id =？'） ; 
 $ stmt-> execute（array（$ id））; 
 $ rows = $ stmt-> fetchAll（PDO :: FETCH_ASSOC）; 
 foreach（$ rows as $ row）{
 // do stuff 
} 
} 
} 
   TableCreator 类在这里需要一个PDO对象才能正常工作，所以将一个PDO对象传递给它是非常合理的当创建一个实例。
 
I just started switching my project form the mysql to PDO. In my project a new PDO Object is created more or less right a the beginning of the programm. 
$dbh_pdo = new PDO("mysql:host=$db_url;dbname=$db_database_name", $db_user, $db_password);
Now I would like to use this handler (is that the correct name?) in some functions and classes. Is there a way to make objects global just like variables or am I trying something unspeakably stupid, because I couldn't find anything when searching the web ...
解决方案
Yes, you can make objects global just like any other variable:
$pdo = new PDO('something');
function foo() {
   global $pdo;
   $pdo->prepare('...');
}
You may also want to check out the Singleton pattern, which basically is a global, OO-style.

That being said, I'd recommend you not to use globals. They can be a pain when debugging and testing, because it's hard to tell who modified/used/accessed it because everything can. Their usage is generally considered a bad practice. Consider reviewing your design a little bit.

I don't know how your application looks like, but say you were doing this:
class TableCreator {
   public function createFromId($id) {
       global $pdo;
       $stmt = $pdo->prepare('SELECT * FROM mytable WHERE id = ?');
       $stmt->execute(array($id));
       $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
       foreach ($rows as $row) {
           // do stuff
       }
   }
}
You should do that instead:
class TableCreator {
   protected $pdo;

   public function __construct(PDO $pdo) {
       $this->pdo = $pdo;
   }

   public function createFromId($id) {
       $stmt = $this->pdo->prepare('SELECT * FROM mytable WHERE id = ?');
       $stmt->execute(array($id));
       $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
       foreach ($rows as $row) {
           // do stuff
       }
   }
}
Since the TableCreator class here requires a PDO object to work properly, it makes perfect sense to pass one to it when creating an instance.

                        
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