How can I use XMLSerializer and XML attributes to deserialize "numbered array"?

[Shea]

I am trying to deserialize an non-standard XML array, returned by some sort of Perl web script, in a VB.NET client application.

Take for example, the following XML:

<MyObject>
  <...other fields...>
  <MyItems>
    <Item1>abcdefg</Item1>
    <Length1>7</Length1>
    <Item2>abcd</Item2>
    <Length2>4</Length2>
    <Item3>abcdefghijk</Item3>
    <Length3>11</Length3>
  </MyItems>
</MyObject>

Below is the class that I've attempted to build to read this XML, simplified of course:

<Serializeable()> _
Public Class MyObject

  'Other fields here

  <XmlArray(ElementName:="MyItems", IsNullable:=True), _
   XmlArrayItem(Type:=GetType(String)), _
   XmlArrayItem(Type:=GetType(Integer))> _
  Public MyItems As ArrayList

End Class

I would like to stick with the XMLSerializer model, instead of using a dataset or LINQ, but I'm open to suggestions.

Thanks in advance,
Shea

[Sfreak]

You can serialize and deserialize the entire class by doing this:

      public static string GenerateXML(this object ObjetoXML)
        {
            MemoryStream MemStream = new MemoryStream();
            StringBuilder xm = new StringBuilder();
            XmlSerializer Serializador = new XmlSerializer(ObjetoXML.GetType());
            XmlTextWriter XmlWrite = new XmlTextWriter(MemStream, Encoding.UTF8);
            long st = MemStream.Length;
            Serializador.Serialize(XmlWrite, ObjetoXML);
            MemStream.Position = 0;
            MemStream.GetHashCode();

            xm.Append(UTF8ByteArrayToString(MemStream.ToArray()));
            return xm.ToString();
        }

   public static object LoadXML(this object Obj, string StrXML)
        {
            XmlSerializer xs = new XmlSerializer(Obj.GetType());
            MemoryStream ms = new MemoryStream(StringToUTF8ByteArray(StrXML));
            Obj = xs.Deserialize(ms);
            return Obj;
        }

        private static String UTF8ByteArrayToString(Byte[] characters)
        {
            UTF8Encoding encoding = new UTF8Encoding();
            String constructedString = encoding.GetString(characters);
            return (constructedString);
        }
        private static Byte[] StringToUTF8ByteArray(String pXmlString)
        {
            UTF8Encoding encoding = new UTF8Encoding();
            Byte[] byteArray = encoding.GetBytes(pXmlString);
            return byteArray;
        }

Note that they are extension methods and must be declared in a static class, but you can use the way you want.

Hope this helps

Fernando

[Shea]

RE: You can serialize and deserialize the entire class by doing this:

Fernando,
Thank you for the quick response. I am already using similar code to deserialize/serialize my objects. I forgot to illustrate that. I use a generic class, that I made (feel free to copy), to encapsulate the serialization code. See below:

<Serializable()> _
Public MustInherit Class XMLSerializable(Of T)

  Public Shared Function XMLDeserialize(ByVal sXML As String) As T
    Dim _ret As T = Nothing
    Dim _xmlBytes() As Byte = Nothing
    Dim _xmlStream As MemoryStream = Nothing
    Dim _serializer As XmlSerializer = Nothing
    Try
      _xmlBytes = UTF8.GetBytes(sXML)
      _xmlStream = New MemoryStream(_xmlBytes)
      _serializer = New XmlSerializer(GetType(T))
      _ret = _serializer.Deserialize(_xmlStream)
    Catch ex As Exception
      _ret = Nothing
    Finally 'Cleanup
      _serializer = Nothing
      If Not IsNothing(_xmlStream) Then
        _xmlStream.Close()
        _xmlStream = Nothing
      End If
      Erase _xmlBytes
      XMLDeserialize = _ret
    End Try
  End Function

  Public Function XMLSerialize() As String
    Dim _ret As String = vbNullString
    Dim _xmlBytes() As Byte = Nothing
    Dim _xmlStream As MemoryStream = Nothing
    Dim _serializer As XmlSerializer = Nothing
    Try
      _xmlStream = New MemoryStream
      _serializer = New XmlSerializer(GetType(T))
      _serializer.Serialize(_xmlStream, Me)
      _xmlStream.Position = 0 'Reset cursor to beginning of stream, after writing serialized object to stream
      ReDim _xmlBytes(_xmlStream.Length - 1) 'Allocate space
      If _xmlStream.Read(_xmlBytes, 0, _xmlStream.Length) Then 'Read the data in the stream
        _ret = UTF8.GetString(_xmlBytes) 'Convert the data, in bytes, to an xml string
        'Take out unneeded xmlns attributes
        _ret = _ret.Replace(" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema""", vbNullString)
        _ret = _ret.Replace("<?xml version=""1.0""?>", vbNullString)
      End If
    Catch ex As Exception
      _ret = vbNullString
    Finally
      XMLSerialize = _ret
    End Try
  End Function

End Class

The MyObject class inherits XMLSerializeabl e(of MyObject). This works for me in many other places. It really should look like this:

<Serializeable()> _ 
Public Class MyObject
  Inherits XMLSerializeable(of MyObject)
  
  'Other fields here 
  
  <XmlArray(ElementName:="MyItems", IsNullable:=True), _ 
   XmlArrayItem(Type:=GetType(String)), _ 
   XmlArrayItem(Type:=GetType(Integer))> _ 
  Public MyItems As ArrayList 
  
End Class

To clarify, the problem is that the XML, contains two "numbered" arrays, inside the MyItems object. When I try to deserialize, MyItems is empty and I get no exception. I've even tried to specifiy the ElementNames, such as "Item" and "Length", but that does the same thing. The numbers in the name seem to throw it off, somehow. Is there any way to append the array index to the name of array item elements?

P.S. I have a sloppy solution that works, but I have to modify the incoming XML to take out the numbers in the names. I don't want to do that. I would like to use an XML attribute to control serialization, to make the code more reliable over time.

Thanks again,
Shea

[Sfreak]

Shea,

I cant figure it out what you want yet.

Notice that this code that i wrote serializes all kind of classes (even your own types with complex or primitive attributes) by applying an extension to the Object class (in the end all we have is an object)

So if you show us what are exactly these numbered arrays we can see it cleary.

att,

Fernando