serialization and inheritance
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Thread: serialization and inheritance

  1. #1
    Join Date
    Apr 2005
    Posts
    7

    serialization and inheritance

    I have a few custom controls, inherited from CompositeControl. I implement ISerializable for each control. This is one example:
    [
    AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal),
    AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal),
    DefaultProperty("ID"),
    ToolboxData("<{0}:EddRadioButtonList runat=\"server\"> </{0}:EddCheckBox>"),
    Serializable
    ]
    public class EddRadioButtonList : CompositeControl, IChannelControl,ISerializable
    {

    ...
    #region ISerializable_implementation
    [SecurityPermissionAttribute(SecurityAction.Demand, SerializationFormatter = true)]
    public void GetObjectData(SerializationInfo info, StreamingContext context)
    {
    info.FullTypeName = EDDQuestionID().ToString();
    info.AddValue("ControlType", GetType().Name);
    info.AddValue("ControlID", ID);
    info.AddValue("Question", Question);
    info.AddValue("Answer", EDDAnswerValue());

    }
    #endregion
    ...
    }


    I have a custom collection of these control. I also mark [Serializable]:
    [Serializable]
    public class EddControlCollection : CollectionBase
    {
    ....
    }

    In my main class, I serialize and deserialize the collection of controls:

    public void Serialize()
    {
    Stream s = File.Open("EDDTemp.xml", FileMode.Create);
    //SoapFormatter formatter = new SoapFormatter();
    BinaryFormatter formatter = new BinaryFormatter();
    formatter.Serialize(s, _EDDControls);
    s.Close();
    }
    public void Deserialize()
    {
    if (File.Exists("EDDTemp.xml"))
    {

    Stream s = File.Open("EDDTemp.xml", FileMode.Open);
    //SoapFormatter formatter = new SoapFormatter();
    BinaryFormatter formatter = new BinaryFormatter();
    _EDDControls = (EddControlCollection)formatter.Deserialize(s);
    //object o = formatter.Deserialize(s);
    s.Close();
    }
    }

    I have an error when I call Deserialize( ). It complained that the constructor to deserialize an object of type '....EddSubmitButton' was not found. EddSubmitButton is one of my custom control. How can I deserialize the custom controls properly?

    I'm thinking I only want to serialize enough information to recreate the controls on the fly, but I seem to have a problem.

    Thanks in advance.

  2. #2
    Join Date
    Apr 2005
    Posts
    7

    Re: serialization and inheritance

    I figured out my own issue. I thought I post it here, in case somebody has the same issue.

    I have to implement the deserialization constructor for each control because formatter.Deserialize() will call the constructor of each control in the collection. The deserialization constructor looks like this:

    //deserialization constructor
    public EddRadioButtonList(SerializationInfo info, StreamingContext context)
    {
    ....
    }

    Most web sites tell you to implement ISerializable, but they don't tell you to implement the deserialzation constructor. You need this constructor for deserialization to work.

    Happy coding

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