Deserializing problem in Managed App

[emmaUK]

Hi everyone!

I'm developing a C++/CLR Windows Forms app in visual Studio 05.

I wanted the user to be able to save the current state of the form which I acheived by serializing the form with the code in my 'Save' function:

// I have created a class 'MyPersistantData' to store the forms
// state
// Serialize the form state to an XML file

MyPersistantData^ dat = gcnew MyPersistantData;

TextWriter^ writer = gcnew StreamWriter(saveFileDialog->FileName );
XmlSerializer ^ myXmlSerializer = gcnew XmlSerializer(dat->GetType() );
myXmlSerializer->Serialize( writer, dat );
writer->Close();

This worked great and saved all my form variables to an XML file.

However I am having major problems trying to de-serialize. This is the code in my 'Open' function I have so far:

MyPersistantData^ dat = gcnew MyPersistantData;

XmlSerializer^ myXmlDeSerializer =
gcnew XmlSerializer( dat->GetType() );
FileStream^ reader =
gcnew FileStream(openFileDialog->FileName, FileMode::Open );
XmlReader^ XReader = gcnew XmlTextReader( reader );
// These lines are fine.

// But the following line throws an exception during runtime:

dat = dynamic_cast< MyPersistantData^ >
(myXmlDeSerializer->Deserialize( reader ) );

Do I need to overload the assignment operator for this class or is there something else i need to do?

Cheers

Emma

[Banfa]

Do I need to overload the assignment operator for this class or is there something else i need to do?

Understanding that I have little experience of .NET 2.0 (and the little experience I have makes me shudder, Microsoft appear to to trying to burry the real code in Windows so far under their absraction layers that they no longer resemble actual C++).

Anyway, you may need to overload the assignment operator in MyPersistantData, but only really if it contains pointer members with allocated data. Also I would not really have expected the lack of an assignment operator to cause an exception imediately but to cause one further down the line when it is harder to detect.

I would look to the exception you are getting, it should give you some clues as to what is going on, Deserialize can raise an exception so it may be how you are using the class.

Good Luck.

[emmaUK]

Thankyou Banfa

I have narrowed the problem down somewhat. Remember that I can get it to Serialize fine but just not De-Serialize.

If I remove the following line of code from my persistant class it NOW De-Serializes so this data member is the problem:

ListBox::ObjectCollection^ listBoxItemsCollection;

So deserializing the ObjectCollection handle is causing the problem.

Seems strange that it Serializes this ok.

Any Ideas?

Emma.