basically i made a page where the user can posts , after he posts it shows in the home page with others posts , i want to make a page that shows the posts that the user posted only
i made this interface with flutter

when i click at the posts page , i get a message shows Failed to load posts even tho the user has posted before

class UserPostsPage extends StatefulWidget {
  @override
  State<UserPostsPage> createState() => _UserPostsPageState();
}

class _UserPostsPageState extends State<UserPostsPage> {
  List userPosts = [];

  @override
  void initState() {
    super.initState();
    fetchUserPosts();
  }

  Future<void> fetchUserPosts() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    String? userId = prefs.getString('userid');
    if (userId != null) {
      var url = Uri.parse("$GETMYPOSTS?userId=$userId");
      var response = await http.get(url, headers: {"Accept": "application/json"});
      if (response.statusCode == 200) {
        var jsonData = json.decode(response.body);
        setState(() {
          userPosts = jsonData;
        });
      } else {
        print('Failed to load posts');
      }
    }
  }
.....
  

and this is the php code :

<?php 

include("../connect.php");

$userid = isset($_GET['userid']) ? $_GET['userid'] : null;

if (!$userid) {
   
    http_response_code(400); 
    echo json_encode(['error' => 'User ID is required']);
    exit;
}
$stmt = $con->prepare("SELECT * FROM post_table WHERE author = ?");
$stmt->bind_param("s", $userid); 

$list = array();

if ($stmt->execute()) {
    $result = $stmt->get_result();
    while ($row = $result->fetch_assoc()) {
        $list[] = $row;
    }
    echo json_encode($list);
} else {
  
    http_response_code(500); 
    echo json_encode(['error' => $stmt->error]);
}

$stmt->close();
?>

PS : there are two tables that im using
post_table : author
and user: userid

tbh i dont know where is the problem exactly