Data missing from serialised file

Question

i am serializing a treeview with its nodes , into xml file.

And when i deserialize back from the xml file.

I can't find the whole content of my treeview in the XML.

The problem, that in this treeview I have added a tag with specific type that i got from a cognex sdk. I guess this type is not serializable?

I can't find the tag , i putted before serializing it , here is how I serialize the object:

public static void SaveTree(TreeView tree, string filename)
{
    using (Stream file = File.Open(filename, FileMode.Create))
    {
        BinaryFormatter bf = new BinaryFormatter();
        bf.Serialize(file, tree.Nodes.Cast<TreeNode>().ToList());
    }
}

public static TreeView LoadTree(string filename)
{
    TreeView tree=new TreeView();

    using (Stream file = File.Open(filename, FileMode.Open))
    {
        BinaryFormatter bf = new BinaryFormatter();
        object obj = bf.Deserialize(file);

        TreeNode[] nodeList = (obj as IEnumerable<TreeNode>).ToArray();
        tree.Nodes.AddRange(nodeList);
    }

    return tree;
}

I guess the type is not serialisable , so what should i do ? How can I serialize this object?

Answer 1

First of all your code serializes content in binary format instead of xml but it would not be a problem while serializing and deserializing.

Please be sure that class of object in the Tag property is also serializable or inherits from MarshallByObjectRef. If the class is not serializable then you cannot serialize or deserialize it.

[EDIT]

As per the source code for the Deserialize method. TreeNode has some 'defensive' code around the serialization of Tag (which is a Property wrapping the userData field):

  if (userData != null && userData.GetType().IsSerializable) {
            si.AddValue("UserData", userData, userData.GetType());

So Tag will only be serialized IF it is an explicitly serializable type. Thus, if you are otherwise able to (De)Serialize the TreeNodes correctly it seems likely that you are assigning a non-serializable object to Tag which then gets stripped away by the above code (the only alternative for the TreeNode serialization would be to throw an error).