Question

I have a class that contains a number of standard fields and an arraylist.

Is there any way to serialize the class using an XmlSerializer?

Attempts so far result in an error message saying:

Unhandled Exception: System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: The type XMLSerialization.DataPoints was not  expected. Use  the XmlInclude or SoapInclude attribute  to specify types that are not known statically.

Some cut-down representations of the classes are shown below:

public class StationData {   private DateTime _CollectionDate;   private string _StationID;   private ArrayList _PolledData;    public StationData()   {   }   public DateTime CollectionDate   {     get { return _CollectionDate; }     set { _CollectionDate = value; }   }   public string StationID   {     get { return _StationID; }     set { _StationID = value; }   }   [XmlInclude(typeof(DataPoints))]   public ArrayList PolledData   {     get { return _PolledData; }     set { _PolledData = value; }   } }  public class DataPoints {   private string _SubStationID;   private int _PointValue;    public DataPoints   {   }   public string SubStationID   {     get { return _SubStationID; }     set { _SubStationID = value; }   }   public int PointValue   {     get { return _PointValue; }     set { _PointValue = value; }   } } 

Answer 1

I have had success with the following:

[XmlArray('HasTypeSpecialisations')] [XmlArrayItem('TypeObject', typeof(TypeObject), IsNullable = false)] public List<TypeObject> TypeSpecialisations 

This results in:

<HasTypeSpecialisations>     <TypeObject />     <TypeObject /> </HasTypeSpecialisations> 

In your situation I would try something like:

[XmlArrayItem(typeof(DataPoints))] public ArrayList PolledData 

Based on this link http://msdn.microsoft.com/en-us/library/2baksw0z(VS.85).aspx you should also be able to use this

[XmlElement(Type = typeof(DataPoints))] public ArrayList PolledData