How to Access Object Properties with Invalid or Integer Names in PHP?

How can I access object properties with names like integers or invalid property names?

JSON decoding in PHP often results in objects with properties that have invalid names. This inconsistency makes it difficult to access these properties using standard object syntax.

Accessing Properties with Valid Names

Properties with valid variable names can be accessed using dot notation:

$data = '{ "name": "John Doe" }';
$obj = json_decode($data);
echo $obj->name; // Output: John Doe

Accessing Properties with Invalid Names

Accessing properties with integer or other invalid names is not as straightforward. PHP has a few quirks that can cause errors:

• PHP 7.2 and later allow accessing numeric properties using curly brace syntax:

$data = '{ "42": "The Answer" }';
$obj = json_decode($data);
echo $obj->{'42'}; // Output: The Answer

• However, for all-numeric property names, this syntax still fails:

$data = '{ "123": "Three Digits" }';
$obj = json_decode($data);
echo $obj->{'123'}; // Error: syntax error

• Exceptions to the above rule occur when the object is not derived from an array:

$obj = new stdClass;
$obj->{'123'} = 'Three Digits';
echo $obj->{'123'}; // Output: Three Digits

Practical Solutions

To access properties with invalid names, consider these options:

• Cast to Array Manually:

$obj = json_decode($data);
$arr = (array) $obj->highlighting;
$value = $arr['448364']['Data']['0'];

• Recursive Array Casting:

function recursive_cast_to_array($obj) {
    $arr = (array) $obj;
    foreach ($arr as &$value) {
        if (is_object($value)) {
            $value = recursive_cast_to_array($value);
        }
    }
    return $arr;
}

$arr = recursive_cast_to_array($obj);
$value = $arr['highlighting']['448364']['Data']['0'];

• Use JSON Functions:

$arr = json_decode(json_encode($obj), true);
$value = $arr['highlighting']['448364']['Data']['0'];

Note that JSON functions require UTF-8 encoding for all strings.

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