Serializable and adding fields

[Steve Teeples]

I have a simple class that is Serializable() so that I can read/write it
to/from disk. Functionally it works great. However, I soon learned that if
I added a field or property to the class that I could no longer read the
"old" data that was written. The error I get says that the component number
no longer matches. Is there a way to tell the reader to ignore the mismatch
and continue reading the data that is currently in the file?
--
Steve

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

Steve,

In order to do this, you will have to implement the ISerializable
interface and handle the writing of the values yourself. If the field
doesn't exist, then you can just ignore it in your implementation.

I'm not sure, but I believe that there is a new attribute in .NET 2.0
which will allow you to specify that certain fields can be ignored if they
are not found.

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

"Steve Teeples" <St**********@discussions.microsoft.com> wrote in message
news:C3**********************************@microsof t.com...

I have a simple class that is Serializable() so that I can read/write it
to/from disk. Functionally it works great. However, I soon learned that
if
I added a field or property to the class that I could no longer read the
"old" data that was written. The error I get says that the component
number
no longer matches. Is there a way to tell the reader to ignore the
mismatch
and continue reading the data that is currently in the file?
--
Steve

[tgrt]

I think you may be able to do this by implementing the ISerializable
interface and adding a serialization constructor. You may still have
problems with versioning though.

protected MyClass(SerializationInfo info, StreamingContext context)
{
this.MyString = info.GetString("MyString");
this.MyInteger = info.GetInt32("MyInteger");
}

public void GetObjectData(SerializationInfo info, StreamingContext context)
{
info.AddValue("MyString", string);
info.AddValue("MyInteger", int);
}

"Steve Teeples" wrote:

I have a simple class that is Serializable() so that I can read/write it
to/from disk. Functionally it works great. However, I soon learned that if
I added a field or property to the class that I could no longer read the
"old" data that was written. The error I get says that the component number
no longer matches. Is there a way to tell the reader to ignore the mismatch
and continue reading the data that is currently in the file?
--
Steve

[Steve Teeples]

Nicholas, thanks for responding! Is there an example somewhere of how to
properly overwrite the ISerializable interface?

"Nicholas Paldino [.NET/C# MVP]" wrote:

Steve,

In order to do this, you will have to implement the ISerializable
interface and handle the writing of the values yourself. If the field
doesn't exist, then you can just ignore it in your implementation.

I'm not sure, but I believe that there is a new attribute in .NET 2.0
which will allow you to specify that certain fields can be ignored if they
are not found.

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

"Steve Teeples" <St**********@discussions.microsoft.com> wrote in message
news:C3**********************************@microsof t.com...

I have a simple class that is Serializable() so that I can read/write it
to/from disk. Functionally it works great. However, I soon learned that
if
I added a field or property to the class that I could no longer read the
"old" data that was written. The error I get says that the component
number
no longer matches. Is there a way to tell the reader to ignore the
mismatch
and continue reading the data that is currently in the file?
--
Steve

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

Steve,

Check out the section of the .NET framework documentation titled "Custom
Serialization" located at (watch for line wrap):

http://msdn.microsoft.com/library/de...ialization.asp
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Steve Teeples" <St**********@discussions.microsoft.com> wrote in message
news:2A**********************************@microsof t.com...

Nicholas, thanks for responding! Is there an example somewhere of how to
properly overwrite the ISerializable interface?

"Nicholas Paldino [.NET/C# MVP]" wrote:

Steve,

In order to do this, you will have to implement the ISerializable
interface and handle the writing of the values yourself. If the field
doesn't exist, then you can just ignore it in your implementation.

I'm not sure, but I believe that there is a new attribute in .NET 2.0
which will allow you to specify that certain fields can be ignored if
they
are not found.

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

"Steve Teeples" <St**********@discussions.microsoft.com> wrote in message
news:C3**********************************@microsof t.com...

>I have a simple class that is Serializable() so that I can read/write it
> to/from disk. Functionally it works great. However, I soon learned
> that
> if
> I added a field or property to the class that I could no longer read
> the
> "old" data that was written. The error I get says that the component
> number
> no longer matches. Is there a way to tell the reader to ignore the
> mismatch
> and continue reading the data that is currently in the file?
> --
> Steve