serializing session state in asp.net

Question

I'm trying to store session state in SQL instead of InProc in our nopcommerce 1.9 install. When I make the requisite changes to the web.config I get this error:

Server Error in '/' Application.

Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SerializationException: Type 'NopSolutions.NopCommerce.BusinessLogic.Categories.Category' in Assembly 'Nop.BusinessLogic, Version=1.9.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.]
System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type) +9449041
System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context) +247
System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo() +160 System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Type objectType, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, SerializationBinder binder) +371
System.Runtime.Serialization.Formatters.Binary.ObjectWriter.WriteArray(WriteObjectInfo objectInfo, NameInfo memberNameInfo, WriteObjectInfo memberObjectInfo) +205 System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Write(WriteObjectInfo objectInfo, NameInfo memberNameInfo, NameInfo typeNameInfo) +651
System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck) +444 System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck) +133 System.Web.Util.AltSerialization.WriteValueToStream(Object value, BinaryWriter writer) +1762

[HttpException (0x80004005): Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode.]
System.Web.Util.AltSerialization.WriteValueToStream(Object value, BinaryWriter writer) +1847
System.Web.SessionState.SessionStateItemCollection.WriteValueToStreamWithAssert(Object value, BinaryWriter writer) +34
System.Web.SessionState.SessionStateItemCollection.Serialize(BinaryWriter writer) +638
System.Web.SessionState.SessionStateUtility.Serialize(SessionStateStoreData item, Stream stream) +244
System.Web.SessionState.SessionStateUtility.SerializeStoreData(SessionStateStoreData item, Int32 initialStreamSize, Byte[]& buf, Int32& length, Boolean compressionEnabled) +67
System.Web.SessionState.SqlSessionStateStore.SetAndReleaseItemExclusive(HttpContext context, String id, SessionStateStoreData item, Object lockId, Boolean newItem) +140
System.Web.SessionState.SessionStateModule.OnReleaseState(Object source, EventArgs eventArgs) +807
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +148 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

Somebody PLEASE tell me I don't need to serialize every object in Nopcommerce to do this!

Answer 1

As the exception says your Type

NopSolutions.NopCommerce.BusinessLogic.Categories.Category

is not serializable. I dont know the implementation of that type but you can try to decorate the type with the [Serializable] attribute.

If you cant do this you can simply write the id of the object to your session.

If you want your session stored in sql server, every object your write into your session needs to be serializable.

More Information

• Steps for Session InProc Mode to Session StateServer

Answer 2

Adding the [Serializable] attribute (<Serializable()> in VB) automatically makes your class serializable. All the members in your class need to be serializable too. So suppose there are object references in your class. Then the classes which those objects belong to need to have the [Serializable] attribute too. Basic types are automatically serializable.