Question

is it possible to use C# XmlSerialization API to store single class in two different ways ?
For example

class Test
{
     int group1_attr1;
     int group1_attr2;
     int group2_attr1;
}

I would like to have a way how to split class fields into two parts(groups – with specified attributes) and each time I call Serialize to control which part will be stored. For example if saving as group1

<?xml version="1.0" encoding="utf-8"?>
<Test xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org  /2001/XMLSchema">
<group1_attr1>0</group1_attr1>
<group1_attr2>0</group1_attr2>
</Test>

if saving as group2

<?xml version="1.0" encoding="utf-8"?>
<Test xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org  /2001/XMLSchema">
<group2_attr1>0</group2_attr1>
</Test>

Is there a way how to do it in a “clean” way ? If not in xmlserialization then in binary perhaps ?
Then I would like to know what is the best way how to merge those two files into single instance of Test. (Note that fields from group1 and group2 do not overlap)

Answer 1

Here’s code demonstrating how to serialize like you want, however, deserialization will be more tricky because it’s not straightforward to deserialize into an existing instance (see How to use XmlSerializer to deserialize into an existing instance?).

public class Test
{
  public int group1_attr1;
  public int group1_attr2;
  public int group2_attr1;
}

class Program
{
  static void Main(string[] args)
  {
     System.Xml.Serialization.XmlAttributes xa = 
        new System.Xml.Serialization.XmlAttributes();
     xa.XmlIgnore = true;
     System.Xml.Serialization.XmlAttributeOverrides xo1 = 
        new System.Xml.Serialization.XmlAttributeOverrides();
     xo1.Add(typeof(Test), "group1_attr1", xa);
     xo1.Add(typeof(Test), "group1_attr2", xa);

     System.Xml.Serialization.XmlAttributeOverrides xo2 = 
        new System.Xml.Serialization.XmlAttributeOverrides();
     xo2.Add(typeof(Test), "group2_attr1", xa);

     System.Xml.Serialization.XmlSerializer xs1 = 
        new System.Xml.Serialization.XmlSerializer(typeof(Test), xo1);
     System.Xml.Serialization.XmlSerializer xs2 = 
        new System.Xml.Serialization.XmlSerializer(typeof(Test), xo2);

     Test t1 = new Test();
     t1.group1_attr1 = 1;
     t1.group1_attr2 = 2;
     t1.group2_attr1 = 3;
     using (System.IO.StringWriter sw = new System.IO.StringWriter())
     {
        xs1.Serialize(sw, t1);
        Console.WriteLine(sw);
     }

     using (System.IO.StringWriter sw = new System.IO.StringWriter())
     {
        xs2.Serialize(sw, t1);
        Console.WriteLine(sw);
     }
  }
}

The deserialization could maybe merge the XML before deserializing:

     Test t2 = new Test();
     System.Xml.Serialization.XmlSerializer xs3 = new System.Xml.Serialization.XmlSerializer(typeof(Test));
     string mergedXml = MergeSerializedXml(group1, group2);

     using (System.IO.StringReader sr = new System.IO.StringReader(mergedXml))
     {
        t2 = (Test)xs3.Deserialize(sr);
     }
...

  static string MergeSerializedXml(string x1, string x2)
  {
     System.Xml.XmlDocument xd = new System.Xml.XmlDocument();
     xd.LoadXml(x1);
     System.Xml.XmlReaderSettings xrs = new System.Xml.XmlReaderSettings();
     xrs.IgnoreWhitespace = true;
     using (System.Xml.XmlReader xr = System.Xml.XmlReader.Create(new System.IO.StringReader(x2), xrs))
     {
        while (xr.Read() && !xr.IsStartElement())
           ;
        xr.MoveToContent();
        xr.Read();
        System.Xml.XmlNode xn = xd.ChildNodes[1];
        do
        {
           xn.AppendChild(xd.ReadNode(xr));
        } while (xr.NodeType != System.Xml.XmlNodeType.EndElement);
     }
     return xd.OuterXml;
  }