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Suppose you have this array:

$object = array ('a' => array ( 'b' => array('c' = 'value'), 'd' => 3)); $indices = array ('a', 'b', 'c');

Is there an easy way to access $object['a']['b']['c'] (keys from $indices array)?

This is what I tried:

function accessObjectKey ($object, $levels) { if (is_string($levels)) $levels = explode ('.', $levels); // for ($i=0; $i<count($levels); $i++) { if ($i == count($levels) && key_exists($levels[$i], $object)) { $value = $object[$levels[$i]]; } else { $value = accessObjectKey ($object, array_shift($levels)); } } return $value; }

Thank you

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  • what are you sending in $levels parameter of function? Commented Jan 31, 2015 at 18:38
  • The first thing that comes to mind is a recursive function. Commented Feb 1, 2015 at 0:31

3 Answers 3

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2

First of all (you have typo array('c' = 'value'), should be array('c' => 'value'),) I tried to use your code:

$object = array ('a' => array ( 'b' => array('c' => 'value'), 'd' => 3)); $indices = array ('a', 'b', 'c'); echo accessObjectKey($object,$indices);

that returned me an error:

Fatal error: Maximum function nesting level of '100' reached, aborting!

I was little bit confusing by your function code, so sorry I created mine It is not perfect but return value as expected:

function getByPath($arr,$path) { if (!isset($arr[$path[0]])) { return 'There is no '.$path[0].' element!'; } elseif(count($path)==1) { return $arr[$path[0]]; } elseif(!is_array($arr[$path[0]])) { return 'Element '.$path[0].' is not array! '; } else { $key = array_shift($path); return getByPath($arr[$key],$path); } } $object = array ('a' => array ( 'b' => array('c' => 'value'), 'd' => 3)); $indices = array ('a', 'b', 'c'); echo getByPath($object,$indices);

output:

value

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Here's another option, from https://baohx2000.medium.com/reaching-deep-into-arrays-using-array-reduce-in-php-9ff9e39a9ca8

function getArrayPath(array $path, array $deepArray) { $reduce = function(array $xs, $x) { return ( array_key_exists($x, $xs) ) ? $xs[$x] : null; }; return array_reduce($path, $reduce, $deepArray); } $x = [ 'a' => 1, 'b' => [ 'c' => 2, 'd' => [3, 4, 5], ], ]; print_r(getArrayPath(['b','d', 0], $x)); // 3
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Another technique is to use explicit stacking.

I came upon this page while searching for related techniques for this CodeReview question.

By "stacking", I actually mean iterate the array of keys which dictate the path to the desired array value and each time a key is found, overwrite the parent array with the newly encountered subarray.

Code: (Demo)

function getFromKeyPath(array $array, array $keys) { foreach ($keys as $index => $key) { if (!key_exists($key, $array)) { throw new Exception("key $key not found at level index $index"); } $array = $array[$key]; } return $array; } $array = ['a' => ['b' => ['c' => 'value'], 'd' => 3]]; $keys = ['a', 'b', 'c']; try { var_export(getFromKeyPath($array, $keys)); } catch (Exception $e) { echo $e->getMessage(); } // 'value'
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