How to serialize multiple objects into an existing XmlDocument, without having the namespaces on each component?

Question

How to serialize multiple objects into a existing XmlDocument in .Net/C#?

I have a XmlDocument, which already contains data. I have multiple objects. Now I want to s

Answer 1

This will serialize objects and append them to a XmlDocument. While de-/serializing the code will resolve the namespaces. @Alex: Thanks for the example with XPathNavigator.

void test2()
{
    XmlDocument doc = new XmlDocument();
    XmlNode root = doc.AppendChild(doc.CreateElement("root"));

    doc.DocumentElement.SetAttribute("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance");
    doc.DocumentElement.SetAttribute("xmlns:xsd", "http://www.w3.org/2001/XMLSchema");

    serializeAppend(root, new object[] { 1, "two", 3.0 });  // serialize object and append it to XmlNode
    var obj = deserialize<object[]>(root.ChildNodes[0]);    // deserialize XmlNode to object
}
T deserialize<T>(XmlNode node)
{
    XPathNavigator nav = node.CreateNavigator();
    using (var reader = nav.ReadSubtree())
    {
        var serializer = new XmlSerializer(typeof(T));
        return (T)serializer.Deserialize(reader);
    }
}
void serializeAppend(XmlNode parentNode, object obj)
{
    XPathNavigator nav = parentNode.CreateNavigator();
    using (var writer = nav.AppendChild())
    {
        var serializer = new XmlSerializer(obj.GetType());
        writer.WriteWhitespace("");
        serializer.Serialize(writer, obj);
        writer.Close();
    }
}

Answer 2

The code below will fulfill the requirement in the OP, to have a clean XML. It will remove all tributes from all elements, but it will add a type attribute to the anyType elements, so the original type could still be distinguish for each element.

static void Main(string[] args)
{
    object[] components = new object[] { new Component_1(), new Component_1() };

    var doc = new XmlDocument();
    doc.Load("source.xml");
    var project = doc.GetElementsByTagName("project")[0];

    var nav = project.CreateNavigator();

    var emptyNamepsaces = new XmlSerializerNamespaces(new[] { 
        XmlQualifiedName.Empty
    });

    foreach (var component in components)
    {
        using (var writer = nav.AppendChild())
        {
            var serializer = new XmlSerializer(component.GetType());
            writer.WriteWhitespace("");
            serializer.Serialize(writer, component
                , emptyNamepsaces
                );
            writer.Close();
        }
    }

    foreach (XmlNode node in doc.GetElementsByTagName("anyType"))
    {
        string attributeType = "";
        foreach (XmlAttribute xmlAttribute in node.Attributes)
        {
            if (xmlAttribute.LocalName == "type")
            { 
            attributeType=xmlAttribute.Value.Split(':')[1];
            }
        }
        node.Attributes.RemoveAll();
        node.CreateNavigator().CreateAttribute("","type","",attributeType);
    }
    doc.Save("output.xml");

}

If you want to deserialize the XML, you'll have to create a dictionary:

static Dictionary<string, Type> _typeCache;

add the expected XML types mapped to corresponding Type values to it:

_typeCache = new Dictionary<string, Type>();
_typeCache.Add("string", typeof(System.String));
_typeCache.Add("int", typeof(System.Int32));
_typeCache.Add("dateTime", typeof(System.DateTime));

and replace each XmlNode in the array by converting it to it's expected type accordingly:

Component_1 c = Deserialize<Component_1>(project.ChildNodes[0].OuterXml);

for (int i = 0; i < c.objectArray.Length; i++)
{
    var type = _typeCache[(((System.Xml.XmlNode[])(c.objectArray[i]))[0]).Value];
    var item = Convert.ChangeType((((System.Xml.XmlNode[])(c.objectArray[i]))[1]).Value, type);
    c.objectArray[i] = item;
}

Console.WriteLine(c.objectArray[0].GetType()); // -> System.String