InfoPath Dev

Is it just possible to store elementary data types in FormState[]? I want to do something like that:

private SPListItemCollection _memberVariable
        {
            get
            {
                return FormState["_memberVariable"] as SPListItemCollection;
            }
            set
            {
                FormState["_memberVariable"] = value;
            }
        }

and access it:

_memberVariable = list.GetItems(query);

Then I get the following exception:

System.Runtime.Serialization.SerializationException was unhandled by user code
  Message="Serialization error."
  Source="Microsoft.Office.InfoPath.Client.Internal.Host"
  StackTrace:
       at Microsoft.Office.InfoPath.Internal.FormStateBagHost.System.Collections.IDictionary.set_Item(Object key, Object value)
       at CommunicationSet.FormCode.set__memberVariable(SPListItemCollection value) in (...)
Microsoft.Office.InfoPath.Internal.ButtonEventHost.OnButtonClick(DocActionEvent pEvent)
       at Microsoft.Office.Interop.InfoPath.SemiTrust._ButtonEventSink_SinkHelper.OnClick(DocActionEvent pEvent)

Hi Kun,

I'm confused by this code - are you writing this in codebehind an InfoPath form or is this a SharePoint web part? Can you give us some context here?

quote:

---

are you writing this in codebehind an InfoPath form or is this a SharePoint web part? Can you give us some context here?

---

It's a codebehind file, "FormCode.cs", VSTA. Not a webpart! Does this help?

You can store any objects in FormState as long as they are serializable. To mark a class as serializable you can add the [System.SerializableAttribute()] to your class definition.

In your case this will not work because SPListItemCollection is already not serializable. One approach here would be to re-create it every time the business logic is called.

Hi!
I have code:
private XPathNavigator mRoot
{
get{return (XPathNavigator)FormState["mRoot"];}
set { FormState["mRoot"] = value; }
}

XPathNavigator is not serializable. How I can use this class in FormState? If I can't use it then how I can create global XPathNavigator variable in browser-enabled form?

 I don't work with browser-enabled forms so I've never used the form state, but could you tell us why you want to store an XPathNavigator globally?  I can't think of a whole lot of reasons why you would need to.

Course, I can store XPathNavigator locally (So I did now), but it is inconvenient. I need for each function to create a new variable.

I'm not sure why it has to be inconvenient.  You could do something like:

private XPathNavigator m_mRoot;
private XPathNavigator mRoot
{
     get
     {
          if(m_mRoot == null)
          {
               m_mRoot = // insert logic to produce mRoot
          }
          return m_mRoot;
     }
}

That will work if mRoot is always supposed to be pointing to the same spot.  Will that work?

That should be easy enough to use.