Exception when deserializing xml file in C#

March 25, 2024

Class:

namespace Biftek
{
    [XmlRoot("Users")]
   
    public class User
    {
        public string username { get; set; }
        public string password { get; set; }
    }
    public class UserManager
    {
        public static List<User> Load(string path)
        {
            List<User> users = new List<User>();
            if(File.Exists(path))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(List<User>));
                using (XmlReader reader = XmlReader.Create(path))
                {
                    users = (List<User>)serializer.Deserialize(reader);
                }
            }
            return users;
        }
    }
}

XML File:

<?xml version="1.0" encoding="utf-8" ?>
<Users>
    <User>
        <username>admin</username>
        <password>admin</password>
    </User>
    <User>
        <username>user</username>
        <password>user</password>
    </User>
</Users>

Exceptions:
System.InvalidOperationException: ‘There is an error in XML document (2, 2).’

Inner Exception
InvalidOperationException: < Users xmlns=”> was not expected.

>Solution :

In your code, the XmlSerializer is expecting to deserialize a List, but your XML file is structured with a root element that contains user elements.

namespace Biftek
{
    [XmlRoot("Users")]
    public class UsersList
    {
        [XmlElement("User")]
        public List<User> Users { get; set; } = new List<User>();
    }

   public class User
   {
        public string username { get; set; }
        public string password { get; set; }
    }

    public class UserManager
    {
        public static List<User> Load(string path)
        {
            UsersList usersList = new UsersList();
            if(File.Exists(path))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(UsersList));
                using (XmlReader reader = XmlReader.Create(path))
                {
                    usersList = (UsersList)serializer.Deserialize(reader);
                }
            }
            return usersList.Users;
        }
    }
}