PHP: Convert a multidimensional array - php

Question

Given the following array:
Array
(
[entity] => Array
(
[title] => Array
(
[empty] => error message
)
[link] => Array
(
[empty] => error message
)
[authors] => Array
(
[0] => Array
(
[full_name] => Array
(
[max_lengh] => another error message 2
)
)
)
)
)
How to convert it into a form like:
$array = [
'entity[title]' => 'error message',
'entity[link]' => 'error message',
'entity[authors][0][full_name]' => 'another error message 2',
];
I think this is done via recursion or use the references but the two things I'm not good)
Thanking you in advance!

Answer 1

You are totally mixed up about array syntax. There is no reason you would want an array like that. Only point to make is that the [empty] becomes [0], you might try var_export to show it better.
What is this for?
$array = [
'entity[title]' => 'error message',
'entity[link]' => 'error message',
'entity[authors][0][full_name]' => 'another error message 2',
];
What even is it...? You have the [] inside the quotes. I mean, you could do very easily
$array2['title'] = $array['title'][0];
etc.
Another thing to address, why you have it like that in the first place?
Anyway, it should work something like this.
foreach ($array as $key => $value)
{
if (isset($value[0]) && !is_array($value[0]))
{
$array[$key] = $value[0];
}
}

Answer 2

Maybe not properly explained to the task.
Thanks to all.
function format(array $array, $withLastKey = false) {
$iterator = new RecursiveIteratorIterator(
new RecursiveArrayIterator($array));
$returnArray = [];
foreach ($iterator as $key => $value) {
$keys = [];
for ($i = $iterator->getDepth(); $i >= 0; $i--) {
$childKey = $iterator->getSubIterator($i)->key();
// if first element then without bracket
$keys[] = ($i == 0) ? $childKey : '[' . $childKey . ']';
}
$keys = array_reverse($keys);
($withLastKey) ?: array_pop($keys);
$returnArray[implode('', $keys)] = $value;
}
return $returnArray;
}