XmlSerializer List Item Element Name

user_248267 0
Viewed 73939

I have a class PersonList

[XmlRoot("Persons")]
PersonList : List<Human>

when I serialize this to XML, by default it will produce something like this:

<Persons>
  <Human>...</Human>
  <Human>...</Human>
</Persons>

My question is what needs to be done in order to change element Human to Person in the output? so the output would be :

<Persons>
  <Person>...</Person>
  <Person>...</Person>
</Persons>

and, how to deserialize the above XML to the PersonList class object?

Per Nick's advice, Here is my testing code:

[XmlRoot("Persons")]
public class Persons : List<Human>
{

}

[XmlRoot("Person")]
public class Human
{
    public Human()
    {
    }

    public Human(string name)
    {
        Name = name;
    }

    [XmlElement("Name")]
    public string Name { get; set; }

}

void TestXmlSerialize()
{
    Persons personList = new Persons();
    personList.Add(new Human("John"));
    personList.Add(new Human("Peter"));

    try
    {
        using (StringWriter writer = new StringWriter())
        {
            XmlSerializer serializer = new XmlSerializer(typeof(Persons));
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.OmitXmlDeclaration = true;

            XmlSerializerNamespaces namespaces = new XmlSerializerNamespaces();
            namespaces.Add(string.Empty, string.Empty);

            XmlWriter xmlWriter = XmlWriter.Create(writer, settings);
            serializer.Serialize(xmlWriter, personList, namespaces);

            Console.Out.WriteLine(writer.ToString());
        }
    }
    catch (Exception e)
    {
        Console.Out.WriteLine( e.ToString());
    }
}

The output of the testing code is:

<Persons>
  <Human>
    <Name>John</Name>
  </Human>
  <Human>
    <Name>Peter</Name>
  </Human>
</Persons>

As the output shows, the [XmlRoot("Person")] on Human does not change the tag to Person from Human.

xmlserializer c#
9 Answers

I don't think there is a way for you to control the name of the generated array elements.

If you can however wrap the Persons collection inside another class you will then have complete control over the generated output using XmlArrayAttribute and XmlArrayItemAttribute.

If you cannot create this new class you can resort to implementing IXmlSerializable, but this is much more complex.

An example for the first alternative follows:

[XmlRoot("Context")]
public class Context
{
    public Context() { this.Persons = new Persons(); }

    [XmlArray("Persons")]
    [XmlArrayItem("Person")]
    public Persons Persons { get; set; }
}

public class Persons : List<Human> { }

public class Human
{
    public Human() { }
    public Human(string name) { Name = name; }
    public string Name { get; set; }
}

class Program
{
    public static void Main(string[] args)
    {
        Context ctx = new Context();
        ctx.Persons.Add(new Human("john"));
        ctx.Persons.Add(new Human("jane"));

        var writer = new StringWriter();
        new XmlSerializer(typeof(Context)).Serialize(writer, ctx);

        Console.WriteLine(writer.ToString());
    }
}
user_2046990

Set the XmlRoot on Human to:

[XmlRoot("Person")]

Sidebar:

Persons should probably be People

user_2276190

If you don't have access to the source for the Human class (in which case, setting XmlRoot is not possible), you can create an XmlElementAttribute, then add it to an XmlAttributeOverride and use that when creating an instance of your XmlSerializer. See this MSDN article for more details.

Nick_224070

I know it's an old question but I ran into the same problem and none of the solutions seems to adresse the OP's question. So here is my solution (comments are in french if you wonder) :

#region Références
using System.Collections.Generic;
using System.Linq;
using System.Xml;
using System.Xml.Schema;
using System.Xml.Serialization;
#endregion

namespace XmlSerializationTests
{
    /// <summary>
    /// Représente une liste qui peut être sérialisée en XML en tant que noeud racine.
    /// </summary>
    /// <typeparam name="T">Type des éléments de la liste.</typeparam>
    public class XmlSerializableList<T>
        : List<T>, IXmlSerializable
    {
        #region Variables
        private static readonly XmlSerializer _ItemSerializer = new XmlSerializer(typeof(T));
        private static readonly string _ItemName;
        private string _RootName;
        #endregion

        #region Méthodes
        /// <summary>
        /// Initialisation statique
        /// </summary>
        static XmlSerializableList()
        {
            _ItemName = (typeof(T).GetCustomAttributes(typeof(XmlRootAttribute), true).FirstOrDefault() as XmlRootAttribute)?.ElementName ?? typeof(T).Name;
        }

        /// <summary>
        /// Obtient le nom racine.
        /// </summary>
        protected virtual string RootName
        {
            get
            {
                if (string.IsNullOrWhiteSpace(_RootName)) _RootName = (GetType().GetCustomAttributes(typeof(XmlRootAttribute), true).FirstOrDefault() as XmlRootAttribute)?.ElementName ?? GetType().Name;
                return _RootName;
            }
        }

        /// <summary>
        /// Obtient le nom des éléments.
        /// </summary>
        protected virtual string ItemName
        {
            get { return _ItemName; }
        }

        /// <summary>
        /// Cette méthode est réservée et ne doit pas être utilisée.Lorsque vous implémentez l'interface IXmlSerializable, vous devez retourner la valeur null (Nothing dans Visual Basic) à partir cette méthode et, si la spécification d'un schéma personnalisé est requise, appliquez à la place <see cref="T:System.Xml.Serialization.XmlSchemaProviderAttribute"/> à la classe.
        /// </summary>
        /// <returns> <see cref="T:System.Xml.Schema.XmlSchema"/> qui décrit la représentation XML de l'objet qui est généré par la méthode <see cref="M:System.Xml.Serialization.IXmlSerializable.WriteXml(System.Xml.XmlWriter)"/> et utilisé par la méthode <see cref="M:System.Xml.Serialization.IXmlSerializable.ReadXml(System.Xml.XmlReader)"/>.</returns>
        public XmlSchema GetSchema()
        {
            return null;
        }

        /// <summary>
        /// Génère un objet à partir de sa représentation XML.
        /// </summary>
        /// <param name="reader"><see cref="T:System.Xml.XmlReader"/> source à partir de laquelle l'objet est désérialisé.</param>
        public void ReadXml(XmlReader reader)
        {
            if (!reader.IsEmptyElement)
            {
                reader.ReadStartElement();
                while (reader.NodeType != XmlNodeType.EndElement)
                {
                    T item = (T) _ItemSerializer.Deserialize(reader);
                    Add(item);
                }
                reader.ReadEndElement();
            }
            else reader.ReadStartElement();
        }

        /// <summary>
        /// Convertit un objet en sa représentation XML.
        /// </summary>
        /// <param name="writer"><see cref="T:System.Xml.XmlWriter"/> flux dans lequel l'objet est sérialisé.</param>
        public void WriteXml(XmlWriter writer)
        {
            foreach (var i in this)
            {
                XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
                ns.Add("", "");
                _ItemSerializer.Serialize(writer, i, ns);
            }
        }
        #endregion
    }
}

And here a unit test class to demonstrate use and results :

#region Références
using System.IO;
using System.Text;
using System.Xml.Serialization;
using Microsoft.VisualStudio.TestTools.UnitTesting;
#endregion

namespace XmlSerializationTests
{
    [TestClass]
    public class XmlSerializableListTests
    {
        public class Person
        {
            public string FirstName { get; set; }
            public string LastName { get; set; }
            public int Birth { get; set; }
        }

        [XmlRoot("color")]
        public class ColorDefinition
        {
            [XmlElement("name")] public string Name { get; set; }
            [XmlElement("r")] public int Red { get; set; }
            [XmlElement("g")] public int Green { get; set; }
            [XmlElement("b")] public int Blue { get; set; }
        }

        public class Persons : XmlSerializableList<Person>
        {
        }

        [XmlRoot("colors")]
        public class ColorList : XmlSerializableList<ColorDefinition>
        {
        }

        private T ReadXml<T>(string text) where T : class
        {
            XmlSerializer serializer = new XmlSerializer(typeof (T));
            using (StringReader sr = new StringReader(text))
            {
                return serializer.Deserialize(sr) as T;
            }
        }

        private string WriteXml<T>(T data) where T : class
        {
            XmlSerializer serializer = new XmlSerializer(typeof(T));
            StringBuilder sb = new StringBuilder();
            using (StringWriter sw = new StringWriter(sb))
            {
                serializer.Serialize(sw, data);
                return sb.ToString();
            }
        }

        [TestMethod]
        public void ReadEmpty()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfInt32>
</XmlSerializableListOfInt32>";
            XmlSerializableList<int> lst = ReadXml<XmlSerializableList<int>>(xml);
            Assert.AreEqual(0, lst.Count);
        }

        [TestMethod]
        public void ReadEmpty2()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfInt32 />";
            XmlSerializableList<int> lst = ReadXml<XmlSerializableList<int>>(xml);
            Assert.AreEqual(0, lst.Count);
        }

        [TestMethod]
        public void ReadSimpleItems()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfInt32>
  <int>0</int>
  <int>52</int>
  <int>79</int>
</XmlSerializableListOfInt32>";
            XmlSerializableList<int> lst = ReadXml<XmlSerializableList<int>>(xml);
            Assert.AreEqual(3, lst.Count);
            Assert.AreEqual(0, lst[0]);
            Assert.AreEqual(52, lst[1]);
            Assert.AreEqual(79, lst[2]);
        }

        [TestMethod]
        public void ReadComplexItems()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfPerson>
  <Person>
    <FirstName>Linus</FirstName>
    <LastName>Torvalds</LastName>
    <Birth>1969</Birth>
  </Person>
  <Person>
    <FirstName>Bill</FirstName>
    <LastName>Gates</LastName>
    <Birth>1955</Birth>
  </Person>
  <Person>
    <FirstName>Steve</FirstName>
    <LastName>Jobs</LastName>
    <Birth>1955</Birth>
  </Person>
</XmlSerializableListOfPerson>";
            XmlSerializableList<Person> lst = ReadXml<XmlSerializableList<Person>>(xml);
            Assert.AreEqual(3, lst.Count);
            Assert.AreEqual("Linus", lst[0].FirstName);
            Assert.AreEqual("Torvalds", lst[0].LastName);
            Assert.AreEqual(1969, lst[0].Birth);
            Assert.AreEqual("Bill", lst[1].FirstName);
            Assert.AreEqual("Gates", lst[1].LastName);
            Assert.AreEqual(1955, lst[1].Birth);
            Assert.AreEqual("Steve", lst[2].FirstName);
            Assert.AreEqual("Jobs", lst[2].LastName);
            Assert.AreEqual(1955, lst[2].Birth);
        }

        [TestMethod]
        public void ReadInheritedPersons()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<Persons>
  <Person>
    <FirstName>Linus</FirstName>
    <LastName>Torvalds</LastName>
    <Birth>1969</Birth>
  </Person>
  <Person>
    <FirstName>Bill</FirstName>
    <LastName>Gates</LastName>
    <Birth>1955</Birth>
  </Person>
  <Person>
    <FirstName>Steve</FirstName>
    <LastName>Jobs</LastName>
    <Birth>1955</Birth>
  </Person>
</Persons>";
            Persons lst = ReadXml<Persons>(xml);
            Assert.AreEqual(3, lst.Count);
            Assert.AreEqual("Linus", lst[0].FirstName);
            Assert.AreEqual("Torvalds", lst[0].LastName);
            Assert.AreEqual(1969, lst[0].Birth);
            Assert.AreEqual("Bill", lst[1].FirstName);
            Assert.AreEqual("Gates", lst[1].LastName);
            Assert.AreEqual(1955, lst[1].Birth);
            Assert.AreEqual("Steve", lst[2].FirstName);
            Assert.AreEqual("Jobs", lst[2].LastName);
            Assert.AreEqual(1955, lst[2].Birth);
        }

        [TestMethod]
        public void ReadInheritedColors()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<colors>
  <color>
    <name>red</name>
    <r>255</r>
    <g>0</g>
    <b>0</b>
  </color>
  <color>
    <name>green</name>
    <r>0</r>
    <g>255</g>
    <b>0</b>
  </color>
  <color>
    <name>yellow</name>
    <r>255</r>
    <g>255</g>
    <b>0</b>
  </color>
</colors>";
            ColorList lst = ReadXml<ColorList>(xml);
            Assert.AreEqual(3, lst.Count);
            Assert.AreEqual("red", lst[0].Name);
            Assert.AreEqual(255, lst[0].Red);
            Assert.AreEqual(0, lst[0].Green);
            Assert.AreEqual(0, lst[0].Blue);
            Assert.AreEqual("green", lst[1].Name);
            Assert.AreEqual(0, lst[1].Red);
            Assert.AreEqual(255, lst[1].Green);
            Assert.AreEqual(0, lst[1].Blue);
            Assert.AreEqual("yellow", lst[2].Name);
            Assert.AreEqual(255, lst[2].Red);
            Assert.AreEqual(255, lst[2].Green);
            Assert.AreEqual(0, lst[2].Blue);
        }

        [TestMethod]
        public void WriteEmpty()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfInt32 />";
            XmlSerializableList<int> lst = new XmlSerializableList<int>();
            string result = WriteXml(lst);
            Assert.AreEqual(xml, result);
        }

        [TestMethod]
        public void WriteSimpleItems()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfInt32>
  <int>0</int>
  <int>52</int>
  <int>79</int>
</XmlSerializableListOfInt32>";
            XmlSerializableList<int> lst = new XmlSerializableList<int>() {0, 52, 79};
            string result = WriteXml(lst);
            Assert.AreEqual(xml, result);
        }

        [TestMethod]
        public void WriteComplexItems()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<XmlSerializableListOfPerson>
  <Person>
    <FirstName>Linus</FirstName>
    <LastName>Torvalds</LastName>
    <Birth>1969</Birth>
  </Person>
  <Person>
    <FirstName>Bill</FirstName>
    <LastName>Gates</LastName>
    <Birth>1955</Birth>
  </Person>
  <Person>
    <FirstName>Steve</FirstName>
    <LastName>Jobs</LastName>
    <Birth>1955</Birth>
  </Person>
</XmlSerializableListOfPerson>";
            XmlSerializableList<Person> persons = new XmlSerializableList<Person>
            {
                new Person {FirstName = "Linus", LastName = "Torvalds", Birth = 1969},
                new Person {FirstName = "Bill", LastName = "Gates", Birth = 1955},
                new Person {FirstName = "Steve", LastName = "Jobs", Birth = 1955}
            };
            string result = WriteXml(persons);
            Assert.AreEqual(xml, result);
        }

        [TestMethod]
        public void WriteInheritedPersons()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<Persons>
  <Person>
    <FirstName>Linus</FirstName>
    <LastName>Torvalds</LastName>
    <Birth>1969</Birth>
  </Person>
  <Person>
    <FirstName>Bill</FirstName>
    <LastName>Gates</LastName>
    <Birth>1955</Birth>
  </Person>
  <Person>
    <FirstName>Steve</FirstName>
    <LastName>Jobs</LastName>
    <Birth>1955</Birth>
  </Person>
</Persons>";
            Persons lst = new Persons
            {
                new Person {FirstName = "Linus", LastName = "Torvalds", Birth = 1969},
                new Person {FirstName = "Bill", LastName = "Gates", Birth = 1955},
                new Person {FirstName = "Steve", LastName = "Jobs", Birth = 1955}
            };
            string result = WriteXml(lst);
            Assert.AreEqual(xml, result);
        }

        [TestMethod]
        public void WriteInheritedColors()
        {
            string xml = @"<?xml version=""1.0"" encoding=""utf-16""?>
<colors>
  <color>
    <name>red</name>
    <r>255</r>
    <g>0</g>
    <b>0</b>
  </color>
  <color>
    <name>green</name>
    <r>0</r>
    <g>255</g>
    <b>0</b>
  </color>
  <color>
    <name>yellow</name>
    <r>255</r>
    <g>255</g>
    <b>0</b>
  </color>
</colors>";
            ColorList lst = new ColorList
            {
                new ColorDefinition { Name = "red", Red = 255, Green = 0, Blue = 0 },
                new ColorDefinition { Name = "green", Red = 0, Green = 255, Blue = 0 },
                new ColorDefinition { Name = "yellow", Red = 255, Green = 255, Blue = 0 }
            };
            string result = WriteXml(lst);
            Assert.AreEqual(xml, result);
        }
    }
}
user_11103030

I know it's old but for others that will come -

Before class Human, add [XmlType("Person")] instead of [XmlRoot("Person")]

user_118519080
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