如何确定对象图中的哪个对象引起了SerializationException

Question

I'm deserializing an object and in certain cases it works fine, however in others it fails. The exception is essentially meaningless to me, but there has to be a way to figure out where exactly it failed so i redirect my debugging.

This is the exception:

System.Runtime.Serialization.SerializationException was caught Message="No map for object '201326592'."
Source="mscorlib" StackTrace: at System.Runtime.Serialization.Formatters.Binary._ BinaryParser.ReadObject() at System.Runtime.Serialization.Formatters.Binary. _BinaryParser.Run() at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream) at Analytics.ReportInstance.Open(Stream tStream, Boolean OpenResults) in C:\\Users...path...\\File.vb:line 149 InnerException:

And this is the source code where it is trapped:

    Public Shared Function Open(ByVal tStream As IO.Stream, Optional ByVal OpenResults As Boolean = False) As ReportInstance
        Dim tFormatter As System.Runtime.Serialization.Formatters.Binary.BinaryFormatter = PluginSerializationBinder.CreateSerializer()
        Dim tInstance As ReportInstance
        Try
            If OpenResults Then 'case which always fails
                'open the entire report
                If System.Diagnostics.Debugger.IsAttached Then
                    Console.WriteLine("Deserializing: report results")
                End If
                tInstance = tFormatter.Deserialize(tStream)  'throws exception here
                Return tInstance
            Else  'case which always works (only deserializing part of the object)
                'just open the stub
                If System.Diagnostics.Debugger.IsAttached Then
                    Console.WriteLine("Deserializing: report instance")
                End If
                Dim tInput As New IO.BinaryReader(tStream)
                Dim tLength As Long = tInput.ReadInt64()
                Dim tBytes() As Byte = tInput.ReadBytes(tLength)
                Dim tMem As New IO.MemoryStream(tBytes)
                tInstance = tFormatter.Deserialize(tMem)
                Return tInstance
            End If
        Catch ex As Exception
            If (ex.Message.Contains("blah")) Then
                Throw New UnsupportedException(ex.Message)
            Else
                Throw  'trapped here
            End If
        End Try
    End Function

Thanks, brian

Answer 1

The exception you're seeing is thrown when the object's "map ID" -- an integer identifying its type, which should reference a type definition earlier in the stream -- is not found in the table of types.

Normally this should not happen unless the byte stream is mangled in transit -- or a formatter instance is reused inappropriately.

A BinaryFormatter keeps track of everything it has already processed, and can emit back-references to previously written types and objects (when serializing) or use previously-read data to resolve back-references in current data (when deserializing).