Is it possible to Serialize a LINQ object?

Question

I'd like to serialize some LINQ generated objects and store them in a table as a binary field (Never you mind why). I'd like to be able to write some code that looks something like this:

SerialTestDataContext db = new SerialTestDataContext();

relation_table row = db.relation_tables.First();

MemoryStream memStream = new MemoryStream();
BinaryFormatter bin = new BinaryFormatter();
bin.Serialize(memStream, row);
Console.WriteLine("Serilized successfully");

TestTable tt = new testTable();
tt.data = new System.Data.Linq.Binary(memStream.ToArray());
db.testTables.InsertOnSubmit(tt);
db.SubmitChanges();
Console.WriteLine("Inserted successfully");

Currently that fails even though I've marked the generated classes as [Serializable] because one of the LINQ inherited classes is not. Is it even possible to do this?

Answer 1

Linq classes are partial classes. You can change the definition to mark the classes as implementing ISerializable and then provide the code...

public partial class User : ISerializable
{
  // implement GetObjectData here
}

There might still be issues with deserialization, however (I'm not 100% on this). An alternative is to use xml serialization and implement IXmlSerializable, which has methods for serializing and deserializing, allowing you to control the entire process...

Answer 2

MSDN: Serialization (LINQ to SQL)

Answer 3

With linq-to-sql (from tags), then yes: you can mark the dmbl as serializable, which uses the [DataContract]/[DataMember] approach. You do this by setting the "Serialization Mode" to "Unidirectional" in the designer, or you can do it in the dbml itself:

<Database ... Serialization="Unidirectional">...

You can then use DataContractSerializer or NetDataContractSerializer to write this (as xml or binary respectively). If you need something portable (i.e. not MS/.NET specific), then protobuf-net will serialize data-contracts using the "protocol buffers" spec.

Answer 4

Following Marc Gravell's advice I wrote the following two blocks of code which worked beautifully:

relation_table row = db.relation_tables.First();

MemoryStream memStream = new MemoryStream();
NetDataContractSerializer ndcs = new NetDataContractSerializer();
ndcs.Serialize(memStream, row);

byte[] stuff = memStream.toArray();

memStream = new MemoryStream(stuff);
row = ndcs.Deserialize(memStream);

db.relation_tables.Attach(row);
Console.WriteLine(row.data_table1.somedata + ": " + row.more_data);

The Attach() call fills in the foreign key dependencies for me and associates the item with the data context.