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I've just coded a little function to check and get a deep array value. Basically, I need to return the value or null if it's not set or does not exists, or in general not useful for databases records. I need to check things like $myarray[key1][key2][key3] etc..

function get_array_deep_value(array $array, array $fields){
  $value = $array;

  foreach($fields as $field){
    $v = $value[$field] ?? null;
    if(empty($v) && $v != 0){  // note: using != operator because it will convert '0' to 0 (while !== does not)
      $value = null; 
      break;
    } 
    $value = $v;
  }

  return $value;
}

Any possible improvements? :)

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  • 1
    \$\begingroup\$ What if the deep value that you want is a zero, but your script returns null? If you are going to call empty() that should happen before null coalescing. \$\endgroup\$ Commented Dec 26, 2021 at 22:51
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    \$\begingroup\$ Your break seems like it is part of a protective measure. Would you prefer instead to throw an exception because the path to the desired element suffered a breakage? How do you differentiate between a truly found null and a fallback null? \$\endgroup\$ Commented Dec 26, 2021 at 22:58
  • \$\begingroup\$ @mickmackusa the break is there because if the value is not the one expected or is undefined/null/empty string, I want a null value. If $v == 0, it will return 0, not null. \$\endgroup\$ Commented Dec 28, 2021 at 8:20

1 Answer 1

Reset to default
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I recommend avoiding declaring single-use variables. I also recommend throwing an exception when a broken path is passed into your function. Better variable naming will help others to instantly understand your code.

Code: (Demo)

function get_array_deep_value(array $array, array $levelKeys) {
    foreach ($levelKeys as $index => $key) {
        if (!key_exists($key, $array)) {
            throw new Exception("key $key not found at level index $index");
        }
        $array = $array[$key];
    }
    return $array;
}

$myArray = [
    'one' => [
        'two' => [
            'three' => [
                4
            ]
        ]
    ]
];

$pathArrays = [
    ['one', 'two', 'three'],
    ['one', 'two'],
    ['one'],
    ['two']
];

foreach ($pathArrays as $pathArray) {
    try {
        var_export(get_array_deep_value($myArray, $pathArray));
    } catch (Exception $e) {
        echo $e->getMessage();
    }
    echo "\n---\n";
}
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  • \$\begingroup\$ Hey, key_esists... Wow... Elegant... :) Thank you! But will the exception also break the loop? \$\endgroup\$ Commented Dec 28, 2021 at 8:22
  • \$\begingroup\$ No, it is caught. Add another valid path to test this. \$\endgroup\$ Commented Dec 28, 2021 at 8:22
  • \$\begingroup\$ ' Add another valid path to test this': what do you mean? Anyway, I need always null when the value is not found/valid, since that value will be written on a database field. \$\endgroup\$ Commented Dec 28, 2021 at 8:28
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    \$\begingroup\$ You can assign the fallback variable in the catch body 3v4l.org/rvhX9 or just return null without throwing an exception, but it will be a more professional approach to differentiate truly extracted values from fallback values. \$\endgroup\$ Commented Dec 28, 2021 at 8:38
  • 1
    \$\begingroup\$ Fair enough, then that logical requirement should be expressed in your question and in your project's code. \$\endgroup\$ Commented Dec 28, 2021 at 13:36

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