请教，laravel collect如何获取无限极分类最后的分类id ？

Question

问题描述

laravel查询出的一个无限极分类的数组,目前是三级只有,我想获取最低也就是三级分类的所有id,该如何获取

$arr = [
    [
        'id' => '1',
        'name' => '分类1',
        'pid' => '0',
        'children' => [
            [
                'id' => '2',
                'name' => '分类1-2',
                'pid' => '1',
                'children' => [
                    [
                        'id' => '3',
                        'name' => '分类1-2-3',
                        'pid' => '2',
                    ],
                    [
                        'id' => '4',
                        'name' => '分类1-2-4',
                        'pid' => '2',
                    ]
                ]
            ],
            [
                'id' => '5',
                'name' => '分类1-5',
                'pid' => '1',
                'children' => [
                    [
                        'id' => '6',
                        'name' => '分类1-5-6',
                        'pid' => '5',
                    ],
                    [
                        'id' => '7',
                        'name' => '分类1-5-7',
                        'pid' => '5',
                    ]
                ]
            ]
        ]
    ],
    [
        'id' => '8',
        'name' => '分类8',
        'pid' => '0',
        'children' => [
            [
                'id' => '9',
                'name' => '分类8-9',
                'pid' => '8',
                'children' => [
                    [
                        'id' => '10',
                        'name' => '分类8-9-10',
                        'pid' => '9',
                    ],
                    [
                        'id' => '11',
                        'name' => '分类8-9-11',
                        'pid' => '9',
                    ]
                ]
            ],
            [
                'id' => '12',
                'name' => '分类8-12',
                'pid' => '8',
                'children' => [
                    [
                        'id' => '13',
                        'name' => '分类8-12-13',
                        'pid' => '12',
                    ],
                    [
                        'id' => '14',
                        'name' => '分类8-12-14',
                        'pid' => '12',
                    ]
                ]
            ]
        ]
    ]
];

尝试方法

尝试过
collect(collect($arr)->pluck('children_categories'))->pluck('id')
collect($arr)->pluck('children_categories')能获取到2 3级分类 后面再获取就都是空数据了

期待的结果

$rule = [3, ......];

期望大佬们给个思路或方案,感谢

Answer 1

如果你的 laravel 版本过旧，就用这一段

$sub3 = collect($arr)->pluck('children')->collapse()->pluck('children')->collapse()->pluck('id');
dump($sub3);

如果你的 laravel 版本在 5.5 以上，可以用下面的方法

// 方案 1
$collection = collect($arr)->pluck('children.*.children')->collapse()->collapse()->pluck('id');
// 方案 2
$collection = collect($arr)->pluck('children.*.children')->flatten(2)->pluck('id');