Question

我试图找到（或创建）一个函数。我有一个多维数组：

$data_arr = [
    "a" => [
        "aa" => "abfoo",
        "ab" => [
            "aba" => "abafoo",
            "abb" => "abbfoo",
            "abc" => "abcfoo"
        ],
        "ac" => "acfoo"
    ],
    "b" => [
        "ba" => "bafoo",
        "bb" => "bbfoo",
        "bc" => "bcfoo"
    ],
    "c" => [
        "ca" => "cafoo",
        "cb" => "cbfoo",
        "cc" => "ccfoo"
    ]
];

我想使用单维数组访问一个值，如下所示：

$data_arr_call = ["a", "ab", "abc"];

someFunction( $data_arr, $data_arr_call ); // should return "abcfoo"

这似乎已经是这类事情的功能，我只是不知道要搜索什么。

Answer 1

试试这个

function flatCall($data_arr, $data_arr_call){
    $current = $data_arr;
    foreach($data_arr_call as $key){
        $current = $current[$key];
    }

    return $current;
}

OP的说明：

$current变量以迭代方式构建，如下所示：

flatCall($data_arr, ['a','ab','abc']);

1st iteration: $current = $data_arr['a'];
2nd iteration: $current = $data_arr['a']['ab'];
3rd iteration: $current = $data_arr['a']['ab']['abc'];

您还可以在每次迭代中执行if ( isset($current) ) ...以提供错误检查。

Answer 2

你需要这样的功能：

function getValue($data_arr, $data_arr_call) {
    foreach ($data_arr_call as $index) {
        if (isset($data_arr[$index])) {
            $data_arr = $data_arr[$index];
        } else {
            return false;
        }
    }
    return $data_arr;
}

并像这样使用它：

$data_arr = [
    "a" => [
        "ab" => [
            "abc" => "abbfoo",
        ],
    ],
];
$data_arr_call = ["a", "ab", "abc"];
$value = getValue($data_arr, $data_arr_call);
if ($value) {
    // do your stuff
}

Answer 3

你可以使用这个函数来避免整个数组的副本（使用引用），能够返回一个NULL值（使用array_key_exists而不是isset），并且当抛出异常时路径不存在：

function getItem(&$array, $path) {
    $target = &$array;
    foreach($path as $key) {
        if (array_key_exists($key, $target))
            $target = &$target[$key];
        else throw new Exception('Undefined path: ["' . implode('","', $path) . '"]');
    }
    return $target;
}

演示：

$data = [
    "a" => [
        "aa" => "abfoo",
        "ab" => [
            "aba" => "abafoo",
            "abb" => NULL,
            "abc" => false
        ]
    ]
];

var_dump(getItem($data, ['a', 'ab', 'aba']));
# string(6) "abafoo"
var_dump(getItem($data, ['a', 'ab', 'abb']));
# NULL
var_dump(getItem($data, ['a', 'ab', 'abc']));
# bool(false)
try {
    getItem($data, ['a', 'ab', 'abe']);
} catch(Exception $e) {
    echo $e->getMessage();
}
# Undefined path: ["a","ab","abe"]

请注意，可以改进此功能，例如，您可以测试参数是否为数组。

Answer 4

想发布一个更优雅的解决方案：array_reduce

    $data_arr = [
        "a" => [
            ...
            "ab" => [
                ...
                "abc" => "abcfoo"
            ],
            ...
        ],
        ...
    ];

    $result = array_reduce(["a", "ab", "abc"], function($a, $b) {
        return $a[$b];
    }, $data_arr);

    // returns "abcfoo"

最近，我在更新一些旧代码到ES6时一直使用Javascript Array.reduce()：

JS:
const data_obj = {...};
let result = ['a','ab','abc'].reduce((a, b) => a[b], data_obj);

动态访问多维数组值

4 个答案:

OP的说明：