Object deserialized from XML has default values for some of the fields

Question

I have small issue with deserializing the object of type ReaderAttributes. As you can see, internally it uses OnOff class to set some of the fields to be "ON" or "OFF"

After the object of ReaderAttributes deserialized, all the fields except OnOff are correctly set from XML file, rest are just set to false. I ran through the debugger, to see how ReaderAttributes is being constructed, and noticed that at very end of Sub New() it runs through the Public Sub New() of the OnOff eight times (number of variables of type OnOff in ReaderAttributes).

<Serializable, XmlRoot("ReaderAttributes")>
Public Class ReaderAttributes
    '  <TTY>OFF</TTY>
    Public tty As OnOff
    '  <ECHO>OFF</ECHO>
    Public echo As OnOff
    '  <BAUD>115200</BAUD>
    Public baud As String
    '  <XONXOFF>OFF</XONXOFF>
    Public xonxoff As OnOff
    '  <FIELDSEP>" "</FIELDSEP>
    Public fieldsep As String
    '  <IDREPORT>OFF</IDREPORT>
    Public idreport As OnOff
    '  <NOTAGRPT>OFF</NOTAGRPT>
    Public notagrpt As OnOff
    '  <CHECKSUM>OFF</CHECKSUM>
    Public checksum As OnOff
    '  <IDTRIES>3</IDTRIES>
    Public idtries As Integer
    '  <RDTRIES>3</RDTRIES>
    Public rdtries As Integer
    '  <WRTRIES>3</WRTRIES>
    Public wrtries As Integer
    '  <SELTRIES>1</SELTRIES>
    Public seltries As Integer
    '  <UNSELTRIES>1</UNSELTRIES>
    Public unseltries As Integer
    '  <LOCKTRIES>1</LOCKTRIES>
    Public locktries As Integer
    '  <INITTRIES>1</INITTRIES>
    Public inittries As Integer
    '  <ANTTRIES>1</ANTTRIES>
    Public anttries As Integer
    '  <BRI>ON</BRI>
    Public bri As OnOff
    '  <ANTS>1,2,0,0,0,0,0,0</ANTS>
    Public ants As String
    '  <TAGTYPE>G1</TAGTYPE>
    Public tagtype As String
    '  <EPCIDREPORT>OFF</EPCIDREPORT>
    Public epcidreport As OnOff
    '  <SWTTADDR>18</SWTTADDR>
    Public swttaddr As Integer
    '  <SWTTLEN>1</SWTTLEN>
    Public swttlen As Integer
    '  <POWER>100</POWER>
    Public fieldstrength As String
    Public Sub New()
        tty = New OnOff()
        echo = New OnOff()
        baud = "115200"
        xonxoff = New OnOff()
        fieldsep = " "

        idreport = New OnOff(True)
        idreport.onoff = True

        notagrpt = New OnOff()
        checksum = New OnOff()
        idtries = 3
        rdtries = 3
        wrtries = 3
        seltries = 1
        unseltries = 1
        locktries = 1
        inittries = 1
        anttries = 1
        bri = New OnOff()
        bri.onoff = True
        ants = "1"
        tagtype = "EPCC1G2"
        epcidreport = New OnOff()
        swttaddr = 12
        swttlen = 6
        fieldstrength = "100,100,100,100"
    End Sub
End Class

Public Class OnOff
    Public onoff As Boolean
    Public Sub New()
        onoff = False
    End Sub
    Public Sub New(ByVal val As Boolean)
        onoff = val
    End Sub
    Public Overrides Function ToString() As String
        If Me.onoff Then
            Return "ON"
        Else
            Return "OFF"
        End If
    End Function
End Class

And here is the code to that I have used to deserialize.

Dim serializer As New XmlSerializer(typ)
Dim o As Object 'Object to be deserialized 
Using reader As XmlReader = XmlReader.Create(New StringReader(str))
      o = serializer.Deserialize(reader)

XML (Rather long):

"<?xml version=\"1.0\"?>\" & vbCrLf & \"<ReaderAttributes xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\">\" & vbCrLf & \"  <tty>\" & vbCrLf & \"    <_onoff>false</_onoff>\" & vbCrLf & \"  </tty>\" & vbCrLf & \"  <echo>" & vbCrLf & \"    <_onoff>false</_onoff>\" & vbCrLf & \"  </echo>\" & vbCrLf & \"  <baud>115200</baud>\" & vbCrLf & \"  <xonxoff>\" & vbCrLf & \"    <_onoff>false</_onoff>\" & vbCrLf & \"  </xonxoff>\" & vbCrLf & \"  <fieldsep>\" \"</fieldsep>\" & vbCrLf & \"  <idreport>\" & vbCrLf & \"    <_onoff>true</_onoff>\" & vbCrLf & \"  </idreport>\" & vbCrLf & \"  <notagrpt>\" & vbCrLf & \"    <_onoff>false</_onoff>\" & vbCrLf & \"  </notagrpt>\" & vbCrLf & \"  <checksum>\" & vbCrLf & \"    <_onoff>false</_onoff>\" & vbCrLf & \"  </checksum>\" & vbCrLf & \"  <idtries>3</idtries>\" & vbCrLf & \"  <rdtries>3</rdtries>" & vbCrLf & \"  <wrtries>3</wrtries>\" & vbCrLf & \"  <seltries>1</seltries>\" & vbCrLf & \"  <unseltries>1</unseltries>\" & vbCrLf & \"  <locktries>1</locktries>\" & vbCrLf & \"  <inittries>1</inittries>\" & vbCrLf & \"  <anttries>1</anttries>\" & vbCrLf & \"  <bri>" & vbCrLf & \"    <_onoff>true</_onoff>\" & vbCrLf & \"  </bri>\" & vbCrLf & \"  <ants>1,4</ants>\" & vbCrLf & \"  <tagtype>EPCC1G2</tagtype>\" & vbCrLf & \"  <epcidreport>\" & vbCrLf & \"    <_onoff>false</_onoff>\" & vbCrLf & \"  </epcidreport>\" & vbCrLf & \"  <swttaddr>12</swttaddr>\" & vbCrLf & \"  <swttlen>6</swttlen>\" & vbCrLf & \"  <fieldstrength>100,100,100,100</fieldstrength>\" & vbCrLf & \"</ReaderAttributes>";

Answer 1

For those of you who might have similar issue. Here the solution. All it took to fix the bug, is to remove constructors from the OnOff class, and within the body of the class, and within the body of the class, set the class data members to their default values.

Answer 2

It looks like there is a disconnect between your Public onoff As Boolean member variable name and the <_onoff> element in your XML. You could either rename the variable:

Public _onoff As Boolean

Or use an XmlElement attribute to tell the serializer the element name:

<XmlElement(ElementName:="_onoff")>
Public onoff As Boolean

Either way should get things to deserialize correctly.