XMLArray with different types but same element name and i:type attribute - xml-serialization

Question

I am trying to serialize some data I have into this XML format but not able to achive the same.
The Desired XML output is below:
<?xml version="1.0" encoding="utf-8"?>
<Root xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<Datas>
<Data xmlns="" i:type="DataA">
<Name>A1</Name>
<ADesc>Description for A</ADesc>
</Data>
<Data xmlns="" i:type="DataB">
<Name>B1</Name>
<BDesc>Description for b</BDesc>
</Data>
</Datas>
</Root>
The Classes I created for serialization are as follows:
public class Data
{
[XmlElement("Name")]
public string Name { get; set; }
}
public class DataA : Data
{
[XmlElement("ADesc")]
public string ADesc { get; set; }
}
public class DataB : Data
{
[XmlElement("BDesc")]
public string BDesc { get; set; }
}
[XmlRoot("Root")]
public class Root
{
[XmlArray("Datas")]
[XmlArrayItem(Type = typeof(Data))]
[XmlArrayItem(Type = typeof(DataA))]
[XmlArrayItem(Type = typeof(DataB))]
public List<Data> Datas { get; set; }
}
I use the below method for serializing:
internal static string Serialize(Root obj)
{
var ns = new XmlSerializerNamespaces();
ns.Add("i", "http://www.w3.org/2001/XMLSchema-instance");
XmlSerializer xmlSerializer = new XmlSerializer(typeof(Root));
using (StringWriter textWriter = new StringWriter())
{
xmlSerializer.Serialize(textWriter, obj, ns);
return textWriter.ToString();
}
}
But the output I get is this (which is not correct):
<?xml version="1.0" encoding="utf-8"?>
<Root xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<Datas>
<DataA>
<Name>A1</Name>
<ADesc>Description for A</ADesc>
</DataA>
<DataB>
<Name>B1</Name>
<BDesc>Description for b</BDesc>
</DataB>
</Datas>
</Root>

Answer 1

In order to generate the {http://www.w3.org/2001/XMLSchema-instance}type attribute using XmlSerializer, you need to attach [XmlInclude(typeof(XXX))] for all subclasses XXX of Data to a declared type somewhere in your object graph, i.e. on the Root class or the Data class itself:
//[XmlInclude(typeof(DataA))] /* Could also go here if you prefer. */
//[XmlInclude(typeof(DataB))] /* Could also go here if you prefer. */
public class Data
{
[XmlElement("Name")]
public string Name { get; set; }
}
public class DataA : Data
{
[XmlElement("ADesc")]
public string ADesc { get; set; }
}
public class DataB : Data
{
[XmlElement("BDesc")]
public string BDesc { get; set; }
}
[XmlRoot("Root")]
[XmlInclude(typeof(DataA))]
[XmlInclude(typeof(DataB))]
public class Root
{
[XmlArray("Datas")]
public List<Data> Datas { get; set; }
}
For more information, see Declaring Serialization Types in Troubleshooting Common Problems with the XmlSerializer and also Xsi:type Attribute Binding Support.