在不使用foreach的情况下获取std类值

Question

首先，我感谢阅读这篇文章的所有人。 这是问题所在。 我试图从这个类别数组下的这两个std类中获取category_id，并将它们添加到另一个数组中，如

$categories = array(75,65);

无论如何，我可以在不使用foreach的情况下获得它们吗？ 它已经在foreach中了，我需要这个类别才能继续下一步。

[categories] => Array
(
    [0] => stdClass Object
        (
            [product_category_id] => 83125
            [category_id] => 75
            [product_id] => 10836
            [ordering] => 2
            [category_parent_id] => 51
            [category_type] => product
            [category_name] => Men boxer
            [category_description] => 
            [category_published] => 1
            [category_ordering] => 3
            [category_left] => 34
            [category_right] => 35
            [category_depth] => 5
            [category_namekey] => product_1494167920_122781373
            [category_created] => 1494167920
            [category_modified] => 1502169524
            [category_access] => all
            [category_menu] => 0
            [category_keywords] => men swimsuit, men swimming pants, swimsuit, men swimming suit, long sleeve swimming suit
            [category_meta_description] => Buy men swimming suit at xxxxx, men long sleeve swimsuit and swimming boxer available, Buy 2 FREE shipping
            [category_layout] => 
            [category_page_title] => Men Swim Boxer - xxxxx
            [category_alias] => men-boxer
            [category_site_id] => 
            [category_canonical] => 
            [category_quantity_layout] => 
            [hasbought] => 
        )

    [1] => stdClass Object
        (
            [product_category_id] => 83124
            [category_id] => 65
            [product_id] => 10836
            [ordering] => 43
            [category_parent_id] => 43
            [category_type] => product
            [category_name] => Accessory
            [category_description] => 
            [category_published] => 1
            [category_ordering] => 5
            [category_left] => 87
            [category_right] => 114
            [category_depth] => 4
            [category_namekey] => product_1476761078_750345878
            [category_created] => 1476761078
            [category_modified] => 1502169605
            [category_access] => all
            [category_menu] => 0
            [category_keywords] => accessory, beach accessory, swimming accessory, xxxx
            [category_meta_description] => Shop accessory at xxxx, beach accessory, fashion accessory, gym accessory and many more, Free shipping & speed delivery
            [category_layout] => 
            [category_page_title] => Accessory - xxxxxxx
            [category_alias] => accessory
            [category_site_id] => 
            [category_canonical] => 
            [category_quantity_layout] => 
            [hasbought] => 
        )

)

Answer 1

您可以将array_map与回调函数一起使用。在不了解您的代码的情况下，我可以假设您可以尝试这样的事情：

  function get_category_id($category) {
    return $category['category_id'];
  }
  $category_id = array_map('get_category_id', $categories);

如果要映射的数组数组，您也可以调查call_user_func_array。我自己还在学习PHP，但我认为这应该有帮助

Answer 2

In my mind, this is a job for array_reduce. Each iteration adds to the array as it goes.

http://php.net/manual/en/function.array-reduce.php

<?php
$data = makeSomeData();

$categories = array_reduce($data, function($carry, $item){
    $carry[] = $item->category_id;
    return $carry;
}, []);

print_r($categories);
echo "\n";


function makeSomeData() {
    $input = [65, 165, 265, 365];
    $data = [];
    foreach($input as $id) {
        $a = new stdClass;
        $a->category_id = $id;
        $data[] = $a;        
    }
    return $data;
}

Answer 3

Not sure about the foreach you referred for array or object inside, but for your case, simply do this

$catesTmp[] = array_map( function($item){ 
    return !empty($item->category_id) ? $item->category_id : null;
}, $categories );

It will return results you need.