serialization bug

[Aaron Clamage]

Hi,

Could someone please confirm the following?

I think I have found a subtle .NET serialization bug. It occurs when object
has a list of items containing another object of the same type and both
objects have a non-static member reference to some other static object. In
this case, I get an InvalidArgument exception when I try to access the
non-static member of the child class. I've included a code sample to
clarify. This "bug" is causing a major problem for me. So, if anyone could
confirm it or let me know if I'm doing something wrong, I would be very
appreciative.

Thanks,
Aaron

Here is the sample

[Serializable]
public class A {
private ArrayList children;
private static Pen DPEN = Pens.Black;
private Pen pen = DPEN;

public A() {
children = new ArrayList();
children.Add(new D());
}

public void AddChild(A a) {
children.Add(a);
}

public A Child {
get { return (A)children[0]; }
}

public Pen Pen {
get { return pen; }
}
}

public class PenSurrogate : ISerializationSurrogate {
public void GetObjectData(Object obj, SerializationInfo info,
StreamingContext context) {
Pen pen = (Pen)obj;

info.AddValue("pencolor", pen.PenType == PenType.SolidColor ? pen.Color :
Color.Empty);
}

public Object SetObjectData(Object obj, SerializationInfo info,
StreamingContext context, ISurrogateSelector selector) {
return (Pen)info.GetValue("pencolor", typeof(Pen));
}
}

public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

A a = new A();
A an = new A();
a.AddChild(an);

BinaryFormatter bFormatter = new BinaryFormatter();
SurrogateSelector s = new SurrogateSelector();
s.AddSurrogate(typeof(Pen), new
StreamingContext(StreamingContextStates.All), new PenSurrogate());
bFormatter.SurrogateSelector = s;
MemoryStream stream = new MemoryStream();
bFormatter.Serialize(stream, a);
stream.Seek(0, SeekOrigin.Begin);
A copy = (A)bFormatter.Deserialize(stream);

System.Console.WriteLine(copy.Pen.Color.ToString() );
System.Console.WriteLine(copy.Child.Pen.Color.ToSt ring()); //Causes an
InvalidArgument Exception
}

[Nicholas Paldino [.NET/C# MVP]]

Aaron,

The problem is with your Serialization surrogate. When you assign the
data, you are storing an instance of the color of the Pen. When returning,
you are taking that instance (a Color structure) and trying to cast it to a
pen. What you should do is create a new Pen and set the color, then return
that.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Aaron Clamage" <ac******@nospam.cs.umd.edu> wrote in message
news:%2****************@tk2msftngp13.phx.gbl...

Hi,

Could someone please confirm the following?

I think I have found a subtle .NET serialization bug. It occurs when object has a list of items containing another object of the same type and both
objects have a non-static member reference to some other static object. In this case, I get an InvalidArgument exception when I try to access the
non-static member of the child class. I've included a code sample to
clarify. This "bug" is causing a major problem for me. So, if anyone could confirm it or let me know if I'm doing something wrong, I would be very
appreciative.

Thanks,
Aaron

Here is the sample

[Serializable]
public class A {
private ArrayList children;
private static Pen DPEN = Pens.Black;
private Pen pen = DPEN;

public A() {
children = new ArrayList();
children.Add(new D());
}

public void AddChild(A a) {
children.Add(a);
}

public A Child {
get { return (A)children[0]; }
}

public Pen Pen {
get { return pen; }
}
}

public class PenSurrogate : ISerializationSurrogate {
public void GetObjectData(Object obj, SerializationInfo info,
StreamingContext context) {
Pen pen = (Pen)obj;

info.AddValue("pencolor", pen.PenType == PenType.SolidColor ? pen.Color : Color.Empty);
}

public Object SetObjectData(Object obj, SerializationInfo info,
StreamingContext context, ISurrogateSelector selector) {
return (Pen)info.GetValue("pencolor", typeof(Pen));
}
}

public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

A a = new A();
A an = new A();
a.AddChild(an);

BinaryFormatter bFormatter = new BinaryFormatter();
SurrogateSelector s = new SurrogateSelector();
s.AddSurrogate(typeof(Pen), new
StreamingContext(StreamingContextStates.All), new PenSurrogate());
bFormatter.SurrogateSelector = s;
MemoryStream stream = new MemoryStream();
bFormatter.Serialize(stream, a);
stream.Seek(0, SeekOrigin.Begin);
A copy = (A)bFormatter.Deserialize(stream);

System.Console.WriteLine(copy.Pen.Color.ToString() );
System.Console.WriteLine(copy.Child.Pen.Color.ToSt ring()); //Causes an
InvalidArgument Exception
}

[Aaron Clamage]

Sorry, that was a typo. But, it is not the problem. Even if the following
line is in the SetObjectData method the problem still occurs. In fact, it
occurs for any non-static reference to a static member.

return new Pen(Color.Black);
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:#v**************@TK2MSFTNGP12.phx.gbl...

Aaron,

The problem is with your Serialization surrogate. When you assign the
data, you are storing an instance of the color of the Pen. When returning, you are taking that instance (a Color structure) and trying to cast it to a pen. What you should do is create a new Pen and set the color, then return that.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Aaron Clamage" <ac******@nospam.cs.umd.edu> wrote in message
news:%2****************@tk2msftngp13.phx.gbl...

Hi,

Could someone please confirm the following?

I think I have found a subtle .NET serialization bug. It occurs when object

has a list of items containing another object of the same type and both
objects have a non-static member reference to some other static object.

In

this case, I get an InvalidArgument exception when I try to access the
non-static member of the child class. I've included a code sample to
clarify. This "bug" is causing a major problem for me. So, if anyone

could

confirm it or let me know if I'm doing something wrong, I would be very
appreciative.

Thanks,
Aaron

Here is the sample

[Serializable]
public class A {
private ArrayList children;
private static Pen DPEN = Pens.Black;
private Pen pen = DPEN;

public A() {
children = new ArrayList();
children.Add(new D());
}

public void AddChild(A a) {
children.Add(a);
}

public A Child {
get { return (A)children[0]; }
}

public Pen Pen {
get { return pen; }
}
}

public class PenSurrogate : ISerializationSurrogate {
public void GetObjectData(Object obj, SerializationInfo info,
StreamingContext context) {
Pen pen = (Pen)obj;

info.AddValue("pencolor", pen.PenType == PenType.SolidColor ? pen.Color :

Color.Empty);
}

public Object SetObjectData(Object obj, SerializationInfo info,
StreamingContext context, ISurrogateSelector selector) {
return (Pen)info.GetValue("pencolor", typeof(Pen));
}
}

public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

A a = new A();
A an = new A();
a.AddChild(an);

BinaryFormatter bFormatter = new BinaryFormatter();
SurrogateSelector s = new SurrogateSelector();
s.AddSurrogate(typeof(Pen), new
StreamingContext(StreamingContextStates.All), new PenSurrogate());
bFormatter.SurrogateSelector = s;
MemoryStream stream = new MemoryStream();
bFormatter.Serialize(stream, a);
stream.Seek(0, SeekOrigin.Begin);
A copy = (A)bFormatter.Deserialize(stream);

System.Console.WriteLine(copy.Pen.Color.ToString() );
System.Console.WriteLine(copy.Child.Pen.Color.ToSt ring()); //Causes

an InvalidArgument Exception
}

[Nicholas Paldino [.NET/C# MVP]]

Aaron,

Can you post the definition of D? I would ignore it, but your Child
property returns the first child which is set in the constructor.

Also, if D derives from A, then I can't see how this doesn't result in
an infinite loop (A creates an instance of D, which int turn, creates an
instance of A, etc, etc).

If D doesn't derive from A, then this is an error, because getting the
property A will result in an invalid cast exception.

Could you please post the complete source which compiles?

--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Aaron Clamage" <ac******@nospam.cs.umd.edu> wrote in message
news:eh**************@TK2MSFTNGP11.phx.gbl...

Sorry, that was a typo. But, it is not the problem. Even if the following line is in the SetObjectData method the problem still occurs. In fact, it
occurs for any non-static reference to a static member.

return new Pen(Color.Black);
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in message news:#v**************@TK2MSFTNGP12.phx.gbl...

Aaron,

The problem is with your Serialization surrogate. When you assign the

data, you are storing an instance of the color of the Pen. When returning,

you are taking that instance (a Color structure) and trying to cast it to a

pen. What you should do is create a new Pen and set the color, then

return

that.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Aaron Clamage" <ac******@nospam.cs.umd.edu> wrote in message
news:%2****************@tk2msftngp13.phx.gbl...

Hi,

Could someone please confirm the following?

I think I have found a subtle .NET serialization bug. It occurs when

object

has a list of items containing another object of the same type and both objects have a non-static member reference to some other static object. In

this case, I get an InvalidArgument exception when I try to access the
non-static member of the child class. I've included a code sample to
clarify. This "bug" is causing a major problem for me. So, if anyone

could

confirm it or let me know if I'm doing something wrong, I would be

very appreciative.

Thanks,
Aaron

Here is the sample

[Serializable]
public class A {
private ArrayList children;
private static Pen DPEN = Pens.Black;
private Pen pen = DPEN;

public A() {
children = new ArrayList();
children.Add(new D());
}

public void AddChild(A a) {
children.Add(a);
}

public A Child {
get { return (A)children[0]; }
}

public Pen Pen {
get { return pen; }
}
}

public class PenSurrogate : ISerializationSurrogate {
public void GetObjectData(Object obj, SerializationInfo info,
StreamingContext context) {
Pen pen = (Pen)obj;

info.AddValue("pencolor", pen.PenType == PenType.SolidColor ?

pen.Color

:

Color.Empty);
}

public Object SetObjectData(Object obj, SerializationInfo info,
StreamingContext context, ISurrogateSelector selector) {
return (Pen)info.GetValue("pencolor", typeof(Pen));
}
}

public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

A a = new A();
A an = new A();
a.AddChild(an);

BinaryFormatter bFormatter = new BinaryFormatter();
SurrogateSelector s = new SurrogateSelector();
s.AddSurrogate(typeof(Pen), new
StreamingContext(StreamingContextStates.All), new PenSurrogate());
bFormatter.SurrogateSelector = s;
MemoryStream stream = new MemoryStream();
bFormatter.Serialize(stream, a);
stream.Seek(0, SeekOrigin.Begin);
A copy = (A)bFormatter.Deserialize(stream);

System.Console.WriteLine(copy.Pen.Color.ToString() );
System.Console.WriteLine(copy.Child.Pen.Color.ToSt ring()); //Causes

an InvalidArgument Exception
}

[Aaron Clamage]

I apologize. I had been trying different things. But, you can ignore the
line referencing D. Here is the correct code sample illustrating the bug
(cut directly from the compiling project).

[Serializable]
public class A {
private ArrayList children;
private static Pen DPEN = Pens.Black;
private Pen pen = DPEN;

public A() {
children = new ArrayList();
}

public void AddChild(A a) {
children.Add(a);
}

public A Child {
get { return (A)children[0]; }
}

public Pen Pen {
get { return pen; }
}
}

public class PenSurrogate : ISerializationSurrogate {
public void GetObjectData(Object obj, SerializationInfo info,
StreamingContext context) {
Pen pen = (Pen)obj;
info.AddValue("pencolor", pen.PenType == PenType.SolidColor ? pen.Color :
Color.Empty);
}

public Object SetObjectData(Object obj, SerializationInfo info,
StreamingContext context, ISurrogateSelector selector) {
return new Pen((Color)info.GetValue("pencolor", typeof(Color)));
}
}

public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

A a = new A();
A an = new A();
a.AddChild(an);

BinaryFormatter bFormatter = new BinaryFormatter();
SurrogateSelector s = new SurrogateSelector();
s.AddSurrogate(typeof(Pen), new
StreamingContext(StreamingContextStates.All), new PenSurrogate());
bFormatter.SurrogateSelector = s;
MemoryStream stream = new MemoryStream();
bFormatter.Serialize(stream, a);
stream.Seek(0, SeekOrigin.Begin);
A copy = (A)bFormatter.Deserialize(stream);

System.Console.WriteLine(copy.Pen.Color.ToString() );
System.Console.WriteLine(copy.Child.Pen.Color.ToSt ring()); // Causes an
InvalidArgument exception
}

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:eX**************@TK2MSFTNGP12.phx.gbl...

Aaron,

Can you post the definition of D? I would ignore it, but your Child
property returns the first child which is set in the constructor.

Also, if D derives from A, then I can't see how this doesn't result in
an infinite loop (A creates an instance of D, which int turn, creates an
instance of A, etc, etc).

If D doesn't derive from A, then this is an error, because getting the
property A will result in an invalid cast exception.

Could you please post the complete source which compiles?

--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Aaron Clamage" <ac******@nospam.cs.umd.edu> wrote in message
news:eh**************@TK2MSFTNGP11.phx.gbl...

Sorry, that was a typo. But, it is not the problem. Even if the

following

line is in the SetObjectData method the problem still occurs. In fact, it

occurs for any non-static reference to a static member.

return new Pen(Color.Black);
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote

in

message news:#v**************@TK2MSFTNGP12.phx.gbl...

Aaron,

The problem is with your Serialization surrogate. When you assign the data, you are storing an instance of the color of the Pen. When

returning,

you are taking that instance (a Color structure) and trying to cast it to

a

pen. What you should do is create a new Pen and set the color, then

return

that.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Aaron Clamage" <ac******@nospam.cs.umd.edu> wrote in message
news:%2****************@tk2msftngp13.phx.gbl...
> Hi,
>
> Could someone please confirm the following?
>
> I think I have found a subtle .NET serialization bug. It occurs when object
> has a list of items containing another object of the same type and

both > objects have a non-static member reference to some other static object. In
> this case, I get an InvalidArgument exception when I try to access the > non-static member of the child class. I've included a code sample to > clarify. This "bug" is causing a major problem for me. So, if anyone could
> confirm it or let me know if I'm doing something wrong, I would be very > appreciative.
>
> Thanks,
> Aaron
>
> Here is the sample
>
> [Serializable]
> public class A {
> private ArrayList children;
> private static Pen DPEN = Pens.Black;
> private Pen pen = DPEN;
>
> public A() {
> children = new ArrayList();
> children.Add(new D());
> }
>
> public void AddChild(A a) {
> children.Add(a);
> }
>
> public A Child {
> get { return (A)children[0]; }
> }
>
> public Pen Pen {
> get { return pen; }
> }
> }
>
> public class PenSurrogate : ISerializationSurrogate {
> public void GetObjectData(Object obj, SerializationInfo info,
> StreamingContext context) {
> Pen pen = (Pen)obj;
>
> info.AddValue("pencolor", pen.PenType == PenType.SolidColor ?

pen.Color

:
> Color.Empty);
> }
>
> public Object SetObjectData(Object obj, SerializationInfo info,
> StreamingContext context, ISurrogateSelector selector) {
> return (Pen)info.GetValue("pencolor", typeof(Pen));
> }
> }
>
> public Form1()
> {
> //
> // Required for Windows Form Designer support
> //
> InitializeComponent();
>
> A a = new A();
> A an = new A();
> a.AddChild(an);
>
> BinaryFormatter bFormatter = new BinaryFormatter();
> SurrogateSelector s = new SurrogateSelector();
> s.AddSurrogate(typeof(Pen), new
> StreamingContext(StreamingContextStates.All), new PenSurrogate());
> bFormatter.SurrogateSelector = s;
> MemoryStream stream = new MemoryStream();
> bFormatter.Serialize(stream, a);
> stream.Seek(0, SeekOrigin.Begin);
> A copy = (A)bFormatter.Deserialize(stream);
>
> System.Console.WriteLine(copy.Pen.Color.ToString() );
> System.Console.WriteLine(copy.Child.Pen.Color.ToSt ring());

//Causes an

> InvalidArgument Exception
> }
>
>