Question

I have one XML document which I want to store it inside ViewState so on each post back I do not need to load it from its physical path again. I do not want to store it in SessionState as well.

when I tried to srote it in ViewState I get an error:

Exception Details: System.Runtime.Serialization.SerializationException: Type ‘System.Xml.XmlDocument’ in Assembly ‘System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’ is not marked as serializable.

my property is something like this:

private XmlDocument MyDocument      {
        get
        {
            object viwObj = ViewState["MyDocument"];
            if (viwObj != null)
                return (XmlDocument)viwObj;

            XmlDocument xmlDoc =  GetMyDocument();
            ViewState["MyDocument"] = xmlDoc;

            return xmlDoc;
        }
    }

How can I make an xml document serializable then?

thanks

Answer 1

You could serialize your XmlDocument to an XML string and save that string in the ViewState.

Serialization:

using (var sw = new StringWriter())
using (var xw = new XmlTextWriter(sw))
{
    xmlDoc.WriteTo(xw);
}

ViewState["MyDocument"] = sw.ToString()

Deserialization:

var xmlDoc = new XmlDocument();
xmlDoc.LoadXml((string) ViewState["MyDocument"]);

This sort of serialization does not really fit into a get/set property, so you will most likely want to override the SaveViewState() and LoadViewState() methods of your user control/page, and add the serialization/deserialization logic within these.