PHP动态数组路径访问 [英] PHP dynamic array path access

问题描述

我可以轻松地在会话数组中的子数组中读写。

I can easily write to and read from a sub-array in the session array.

$_SESSION['a']['b']['c']['value']=123;
$val=$_SESSION['a']['b']['c']['value'];

我希望可以定义它，而不是硬编码写入值的位置通过字符串或其他方式。以下内容显然不起作用，但希望可以更好地解释其意图。

Instead of hard coding the "location" where the value is written, I would like it to be definable via a string or some other way. The following will obviously not work, but hopefully will better explain the intent.

$prefix="['a']['b']['c']";  //defined in config page, etc
$_SESSION.$prefix.['value']=123;
$val=$_SESSION.$prefix.['value'];

如何实现？

推荐答案

PropertyAccess

对于此类任务，有一个出色的Symfony组件，名为 PropertyAccess 。您可以按以下方式使用它：

PropertyAccess

There is an excellent Symfony component for such tasks, named PropertyAccess. You can use it as follows:

$persons = array('a' => array('b' => 5.7));
$accessor = PropertyAccess::createPropertyAccessor();
echo $accessor->getValue($persons, '[a][b]'); // 5.7

您可以按照文档中的说明使用Composer安装它，也可以直接从 GitHub 。

You can install it using Composer as described in docs or fetch directly from GitHub.

这是一个完整的解决方案，它的确给我留下了深刻的印象……但是它有效！检查下面的代码， assert（）演示用法：

This is a complete solution, I'm really impressed that it works... but it works! Check the code below, assert()'s demonstrate the usage:

<?php
function arrayPropertyPathGet(array $arr, $path) {
    $parts = explode('.', $path);
    $ret = $arr;
    foreach($parts as $part) {
        $ret = $ret[$part];
        }
    return $ret;
    }

function arrayPropertyPathSet(array &$arr, $path, $value) {
    $parts = explode('.', $path);
    $tmp = &$arr;
    foreach($parts as $part) {
        if(!isset($tmp[$part])) { return false; }
        $tmp = &$tmp[$part];
        }
    $tmp = $value;
    return true;
    }

$test = array('a' => array('b' => 'value'));

assert('value' === arrayPropertyPathGet($test, 'a.b'));
assert(true === arrayPropertyPathSet($test, 'a.b', 'other'));
assert('other' === arrayPropertyPathGet($test, 'a.b'));

侧面注

从理论上讲请注意（不要将其用于学习目的），您可以尝试 eval（），例如：

eval("$value = $persons['a']['b']");

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