PHP Create a multidimensional array from the keys

Is there a way to create dynamicaly multidimensional array? I have stored in database "path" for each field=>value like that:

field_name : [slideshow][slide][0][title]
field_value : my title

field_name : [slideshow][slide][0][desc]
field_value : my desc

field_name : [slideshow][slide][1][title]
field value : my other title

field_name : [slideshow][slide][1][desc]
field value : my other desc

field_name : [slideshow][settings][duration]
field value : 300

and now I'm trying to figure out how to make it an array again. Obviously there can be lots of fields and complexity so I wanted to avoid some recursions if possible, cause I'm not sure how it will impact performance.

I was playing around with variable variables and trying something like:

$array_name = 'arr';
${$array_name}[slideshow][slide][1][title] = $field->field_value;
print_r($arr);

but this works only if its literally that, and nothing like this works:

${$array_name}.$field->field_name = $field->field_value;

I basically need to store every field as individual row (e.g. for searches in those fields), values can be diffrent types (even serialized arrays), and contain html.

Any advice appreciate.

---

The basic idea is to split up your field_name string and loop over the parts backward to build up the array. Some recursion is used to merge the arrays, though any performance impact should be negligible.

---

Example:

// Set up sample data.
$field = new stdClass();
$field->field_name = '[slideshow][slide][0][title]';
$field->field_value = 'my title';
$fields[] = $field;

$field = new stdClass();
$field->field_name = '[slideshow][slide][0][desc]';
$field->field_value = 'my desc';
$fields[] = $field;

$field = new stdClass();
$field->field_name = '[slideshow][slide][1][title]';
$field->field_value = 'my other title';
$fields[] = $field;

$field = new stdClass();
$field->field_name = '[slideshow][slide][1][desc]';
$field->field_value = 'my other desc';
$fields[] = $field;

$field = new stdClass();
$field->field_name = '[slideshow][settings][duration]';
$field->field_value = '300';
$fields[] = $field;
// End sample data.

// array_merge_recursive() doesn't do what we want with numeric keys, so use this
function merge($base, $array) {
    foreach ($array as $key => $value) {
        if (isset($base[$key]) && is_array($base[$key]) && is_array($value)) {
            $base[$key] = merge($base[$key], $value);
        } else {
            $base[$key] = $value;
        }
    }
    return $base;
}

$result = [];
foreach ($fields as $field) {
    $parts  = array_reverse(explode('][', trim($field->field_name, '[]')));
    $value = $field->field_value;
    foreach ($parts as $part) {
        $value = [$part => $value];
    }
    $result = merge($result, $value);
}
print_r($result);

---

Output:

Array
(
    [slideshow] => Array
        (
            [slide] => Array
                (
                    [0] => Array
                        (
                            [title] => my title
                            [desc] => my desc
                        )

                    [1] => Array
                        (
                            [title] => my other title
                            [desc] => my other desc
                        )

                )

            [settings] => Array
                (
                    [duration] => 300
                )

        )

)