Convert array keys from underscore_case to camelCase recursively

Question

I had to come up with a way to convert array keys using undescores (underscore_case) into camelCase. This had to be done recursively since I did not know what arrays will be

Answer 1

You can use preg_replace_callback and change all the keys without to loop on each using array_keys and array_combine:

private function convertKeysToCamelCase($apiResponseArray) {
    $keys = preg_replace_callback('/_(.)/', function($m) {
        return strtoupper($m[1]);
    }), array_keys($apiResponseArray));

    return array_combine($keys, $apiResponseArray);
}

or without regex:

private function convertKeysToCamelCase($apiResponseArray) {
    $keys = array_map(function ($i) {
        $parts = explode('_', $i);
        return array_shift($parts). implode('', array_map('ucfirst', $parts));
    }, array_keys($apiResponseArray));

    return array_combine($keys, $apiResponseArray);
}

You can modify the second function to deal with multidimensional arrays:

private function convertKeysToCamelCase($apiResponseArray) {
    $keys = array_map(function ($i) use (&$apiResponseArray) {
        if (is_array($apiResponseArray[$i]))
            $apiResponseArray[$i] = $this->convertKeysToCamelCase($apiResponseArray[$i]);

        $parts = explode('_', $i);
        return array_shift($parts) . implode('', array_map('ucfirst', $parts));
    }, array_keys($apiResponseArray));

    return array_combine($keys, $apiResponseArray);
}