PHP：\命名空间内的Exception或Exception

Question

我正在尝试处理api中的一些错误。然而，我尝试了这么多方法来执行它所需要做的事情？

在代码中，我使用了Exception，\Exception，另一个扩展为Exception的类"use \Exception“。这些选项都不起作用。我需要做什么来执行块捕获？

  //Piece of source in the begin of file
    namespace Business\Notifiers\Webhook;
    use \Exception;
    class MyException extends \Exception {}

    //Piece of source from my class
    try{

        $products = $payment->getProducts();
        if(count($products) == 0)
            return;
        $flight_id = $products[0]->flight_id;
        $this->message = 'Sir, we have a new request: ';
        $products = null; //Chagind it to null to force an error..
        foreach($products as $product){

            $this->appendAttachment(array(
                'color' => '#432789',
                'text' => 
                    "*Name:* $product->name $product->last_name \n" . 
                    "*Total Paid:*  R\$$product->price\n",
                'mrkdwn_in' => ['text', 'pretext']
            ));
        }
    } catch(Exception $e){
        $this->message = "A exception occurred ";
    } catch(\Exception $e){
        $this->message = "A exception occurred e";
    } catch(MyException $e){
        $this->message = "A exception occurred";
    } 

Answer 1

首先，您需要了解异常和错误之间的区别：

1. http://php.net/manual/en/language.exceptions.php
2. http://php.net/manual/en/ref.errorfunc.php

尝试对空值进行foreach操作不会产生异常，但会触发错误。您可以使用错误处理程序将错误包装在异常中，如下所示：

<?php

function handle ($code, $message)
{
    throw new \Exception($message, $code);
}

set_error_handler('handle');

// now this will fail
try {
    $foo = null;
    foreach ($foo as $bar) {
    }
} catch(\Exception $e) {
    echo $e->getMessage();
}

但是，在您的代码中，您可以简单地检查$products是否为空，如果是，则抛出异常：

if (!$products) {
    throw new \Exception('Could not find any products')
}
foreach($products as $product) { ...

Answer 2

上面接受的答案给出了问题的真正原因，但没有回答主题

如果有人对此感兴趣并正在寻找

命名空间内的Exception和\Exception有什么区别？

对于PHP 7.3.5仍然有效：

1. \ Exception : Refer in root Exception Refer in current namespace
2. PHP does Refer to root namespace，如果在当前名称空间中找不到类，它将发出错误。

<?php
namespace Business;
try {
    throw new Exception("X"); //  Uncaught Error: Class 'Business\Exception' not found
} catch (Exception $e) {
    echo "Exception: " . $e->getMessage();
}

<?php
namespace Business;
class Exception extends \Exception {} // means \Business\Exception extends \Exception

$a = new Exception('hi'); // $a is an object of class \Business\Exception
$b = new \Exception('hi'); // $b is an object of class \Exception