我们可以为 php 中的特定值迭代关联数组吗？

Question

$prod_summary

Array ( [0] => Array ( [ord_id] => 1 [userid] => 1 [tot_qty] => 5 [tot_act_amt] => 239.28))

$prod_list

Array ( [0] => Array ( [ord_id] => 1 [BookName] => My Book update) [1] => Array ( [ord_id] => 1 [BookName] => book908) )

$prod_summary 将有订单摘要，$prod_list 将有与订单相关的产品列表。首先，它应该显示特定订单的订单摘要，然后显示该订单下订购的产品列表。示例：

Order Id: 1
Product Name : Book1
Product Name : Book2
Order Id: 2
Product Name : Book1
Product Name : Book4
Order Id: 3
Product Name : Book3
Product Name : Book4

为了实现这一点，我使用了嵌套循环，但存在问题，因为内循环会为每个外循环迭代的每个元素进行迭代。请参考以下代码：

foreach ($prod_summary as $summary) {
 echo 'Order Id :'.$summary['ord_id'];
foreach ($prod_list as $prod) { // this loop will iterate for all element
    if($prod['ord_id']==$summary['ord_id']){ // comparing ord_id from outer loop 
      echo 'Product Name '.$prod['BookName'];
      }
   }
}

谁能提出更好的解决方案？我们在 php 中是否有任何选项可以让我迭代 inner loop 以获取特定的 ord_id（来自外部循环）以节省一些资源？

Answer 1

foreach($prod_list as $item){
    $pNames[$item['ord_id']] = $item['BookName'];
}
foreach ($prod_summary as $summary) {
     echo 'Order Id :'.$summary['ord_id'].'<br>'
     'Product Name '.$pNames[$summary['ord_id']];
}

Answer 2

使用call_user_func_array、array_merge_recursive、array_keys和array_intersect_key函数的解决方案：

$prod_summary = Array(
    0 => Array('ord_id' => 1, 'userid' => 1, 'tot_qty' => 5, 'tot_act_amt' => 239.28)
);
$prod_list = Array(
    0 => Array('ord_id' => 1, 'BookName' => 'My Book update'),
    1 => Array('ord_id' => 1, 'BookName' => 'book908'),
    2 => Array('ord_id' => 2, 'BookName' => 'book909'),
    3 => Array('ord_id' => 1, 'BookName' => 'book908')
);

// getting grouped list of order ids and booknames with relative positions at once
$groups = call_user_func_array("array_merge_recursive", $prod_list);

foreach ($prod_summary as $summary) {
    echo 'Order Id :' . $summary['ord_id'] . PHP_EOL;
    $ord_keys = array_keys($groups['ord_id'], $summary['ord_id']);

    // outputing booknames only if there's a needed 'ord_id' within $groups array
    if (!empty($ord_keys) && $booknames = array_intersect_key($groups['BookName'], array_flip($ord_keys))) {
        echo implode("", array_map(function($v){ return 'Product Name '. $v. PHP_EOL; }, $booknames));
    }
}

输出：

Order Id :1
Product Name My Book update
Product Name book908
Product Name book908

Answer 3

您可以使用自定义函数来实现您的目标。我为其他可能面临与您现在面临的类似问题的人创建了此功能。

/**

A PHP function to iterate loop for specific value gotten from another array...

@param array1 = main array we are matching against,
@param array2 = array with which we are checking for values matching one in array1.
@param key = the key we expect to see in array2 that exists in array1.
*/
function array_match_key($array1 = [], $array2 = [], $key = null){
    $result = [];
    while(list($var1, $val1) = each($array1)){
        while(list($var2, $val2) = each($array2)){
            if($val1[$key] == $val2[$key]){
                $result = array_merge($result, $val2);
            }
        }
    }
   return $result;
}

可以这样用……以你的情况为例：

$matches = array_match_key($prod_summary, $prod_list, "ord_id");
foreach($matches as $prod){
    echo 'Order Id :'.$prod['ord_id']."<br>";
    echo 'Product Name '.$prod['BookName']."<br>";
}

我不在一个可以测试它的环境中，但它应该可以完美运行。试试看。以后可能会为您节省大量工作。