Is there a way to change all keys in a flat indexed array to the same string ("Name")?

If you have an array of keys that you want to use then use array_combine

Given $keys = array('a', 'b', 'c', ...) and your array, $list, then do this:

$list = array_combine($keys, array_values($list));

List will now be array('a' => 'blabla 1', ...) etc.

You have to use array_values to extract just the values from the array and not the old, numeric, keys.

That's nice and simple looking but array_values makes an entire copy of the array so you could have space issues. All we're doing here is letting php do the looping for us, not eliminate the loop. I'd be tempted to do something more like:

foreach ($list as $k => $v) {
   unset ($list[$k]);
   
   $new_key =  *some logic here*

   $list[$new_key] = $v;
}

I don't think it's all that more efficient than the first code but it provides more control and won't have issues with the length of the arrays.

change array key name "group" to "children".

<?php
echo json_encode($data);

function array_change_key_name( $orig, $new, &$array ) {
    foreach ( $array as $k => $v ) {
        $res[ $k === $orig ? $new : $k ] = ( (is_array($v)||is_object($v)) ? array_change_key_name( $orig, $new, $v ) : $v );
    }
    return $res;
}

echo '<br>=====change "group" to "children"=====<br>';
$new = array_change_key_name("group" ,"children" , $data);
echo json_encode($new);
?>

result:

{"benchmark":[{"idText":"USGCB-Windows-7","title":"USGCB: Guidance for Securing Microsoft Windows 7 Systems for IT Professional","profile":[{"idText":"united_states_government_configuration_baseline_version_1.2.0.0","title":"United States Government Configuration Baseline 1.2.0.0","group":[{"idText":"security_components_overview","title":"Windows 7 Security Components Overview","group":[{"idText":"new_features","title":"New Features in Windows 7"}]},{"idText":"usgcb_security_settings","title":"USGCB Security Settings","group":[{"idText":"account_policies_group","title":"Account Policies group"}]}]}]}]}

=====change "group" to "children"=====

{"benchmark":[{"idText":"USGCB-Windows-7","title":"USGCB: Guidance for Securing Microsoft Windows 7 Systems for IT Professional","profile":[{"idText":"united_states_government_configuration_baseline_version_1.2.0.0","title":"United States Government Configuration Baseline 1.2.0.0","children":[{"idText":"security_components_overview","title":"Windows 7 Security Components Overview","children":[{"idText":"new_features","title":"New Features in Windows 7"}]},{"idText":"usgcb_security_settings","title":"USGCB Security Settings","children":[{"idText":"account_policies_group","title":"Account Policies group"}]}]}]}]}

I did this for an array of objects. Its basically creating new keys in the same array and unsetting the old keys.

public function transform($key, $results)
{
    foreach($results as $k=>$result)
    {
        if( property_exists($result, $key) )
        { 
            $results[$result->$key] = $result;
            unset($results[$k]);
        }
    }

    return $results;
}