array_map strtolower() expects parameter 1 to be string - php

Question

I've got this error Warning: strtolower() expects parameter 1 to be string, array given..
I don't know how I've got my error.. Please help thanks!
$mypages = array(
'Pages' => array('page' => array('view_all_pages', 'add_page', 'dashboard'),
'test' => array('test1', 'test2')),
'Users' => array('vieW_all_users', 'add_user'));
foreach($mypages as $keys => $key):
if(is_array($key)):
$key = array_map('strtolower' ,$key);
endif;
endforeach;

Answer 1

foreach is a loop that will gives you first level of key=>value pairs of an array.
foreach($mypages as $keys => $key){
echo "Key : $keys \n";
echo "Value : ";var_dump($key);
}
will output :
Key : Pages
Value : array('page' => array('view_all_pages', 'add_page', 'dashboard'), 'test'=> array('test1', 'test2')),
Key : Users
Value : array('vieW_all_users', 'add_user')
To make it work, you need to check if the value is an array.
function strtolowerArray(&$arr){
foreach($arr as $k=>$v){
if(is_array($v)){
$arr[$k] = strtolowerArray($v);
}
else if(is_string($v)){
$arr[$k] = strtolower($v);
}
else{
throw new \LogicException("The value is neither a string nor an array");
}
}
return $arr;
}
$mypages = array(
'Pages' => array(
'page' => array('view_ALL_pages', 'aDD_page', 'DaShbOArd'),
'test' => array('test1', 'TEST2')
),
'Users' => array('vieW_all_users', 'aDd_uSer')
);
var_dump(strtolowerArray($mypages));
The '&' in front of the strtolowerArray's parameter means we pass teh variable by reference. If anychanges happens to this variables inside strtolowerArray function's scope, then it will be reflected into the parent scope.

Answer 2

$mypages['Pages']['page'] does not contain a string that can be passed to strtolower().
You should debug by dumping $key inside the loop.

Answer 3

You have arrays in your arrays yo!
You have to iterate into the arrays before asking for (and trying to convert) the values.
Try walking through the array conditionally e.g.
//pseudo
func myRecursion($data = array()) {
foreach($data as $value) {
if(is_array($value)) {
$data = myRecusion($data[$value]);
} else {
//its not an array so do your thing
}
}
return($data);
}