views:

685

answers:

4

I am trying to serialize a class several of the data-members are Nullable objects, here is a example

[XmlAttribute("AccountExpirationDate")]
public Nullable<DateTime> AccountExpirationDate 
{ 
  get { return userPrincipal.AccountExpirationDate; } 
  set { userPrincipal.AccountExpirationDate = value; } 
}

However at runtime I get the error

Cannot serialize member 'AccountExpirationDate' of type System.Nullable`1[System.DateTime]. XmlAttribute/XmlText cannot be used to encode complex types.

However I checked and Nullable is a SerializableAttribute. What am I doing wrong?

+6  A: 

You can only serialize it as an XmlElement, not as an XmlAttribute, as the representation is too complex for an attribute. That's what the exception is telling you.

David M
You can create your own implementation of Nullable<T> however and implement the necessary XML serialization attributes for it.
NickLarsen
Yes, you could, agreed. But the compiler wouldn't treat it in exactly the same way as the built-in `Nullabele<T>`, which has special treatment (thinking of things like implicit definition of `==`). So not recommended.
David M
@NickLarsen - it also won't be able to correctly generate the schema unless you go mad with it.
Marc Gravell
A: 

If you just want it to work, then perhaps:

using System;
using System.ComponentModel;
using System.Xml.Serialization;
public class Account
{
    // your main property; TODO: your version
    [XmlIgnore]
    public Nullable<DateTime> AccountExpirationDate {get;set;}

    // this is a shim property that we use to provide the serialization
    [XmlAttribute("AccountExpirationDate")]
    [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
    public DateTime AccountExpirationDateSerialized
    {
        get {return AccountExpirationDate.Value;}
        set {AccountExpirationDate = value;}
    }

    // and here we turn serialization of the value on/off per the value
    [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
    public bool ShouldSerializeAccountExpirationDateSerialized()
    {
        return AccountExpirationDate.HasValue;
    }

    // test it...
    static void Main()
    {
        var ser = new XmlSerializer(typeof(Account));
        var obj1 = new Account { AccountExpirationDate = DateTime.Today };
        ser.Serialize(Console.Out, obj1);
        Console.WriteLine();
        var obj2 = new Account { AccountExpirationDate = null};
        ser.Serialize(Console.Out, obj2);
    }
}

This will only include the attribute when there is a non-null value.

Marc Gravell
+2  A: 

I've used something like this many times.

[XmlIgnore]
public Nullable<DateTime> AccountExpirationDate 
{ 
    get { return userPrincipal.AccountExpirationDate; } 
    set { userPrincipal.AccountExpirationDate = value; } 
}

///
/// <summary>Used for Xml Serialization</summary>
///
[XmlAttribute("AccountExpirationDate")]
public string AccountExpirationDateString
{
    get
    {
        return AccountExpirationDate.HasValue
            ? AccountExpirationDate.Value.ToString("yyyy/MM/dd HH:mm:ss.fff")
            : string.Empty;
    }
    set
    {
        AccountExpirationDate =
            !string.IsNullOrEmpty(value)
            ? DateTime.ParseExact(value, "yyyy/MM/dd HH:mm:ss.fff")
            : null;
    }
}
fre0n
I think that should be:AccountExpirationDate.Value.ToString("yyyy/MM/dd HH:mm:ss.fff")
Perhentian
Good catch. I've fixed it.
fre0n
A: 

Define a Serializable that encapsulates your funcionality.

Here's are and example.

[XmlAttribute("AccountExpirationDate")]
public SerDateTime AccountExpirationDate
{
get { return _SerDateTime ; }
set { _SerDateTime = value; }
}

/// <summary>
/// Serialize DateTime Class (<i>yyyy-mm-dd</i>)
/// </summary>
public class SerDateTime : IXmlSerializable {
    /// <summary>
    /// Default Constructor when time is not avalaible
    /// </summary>
    public SerDateTime() { }
    /// <summary>
    /// Default Constructor when time is avalaible
    /// </summary>
    /// <param name="pDateTime"></param>
    public SerDateTime(DateTime pDateTime) {
        DateTimeValue = pDateTime;
    }

    private DateTime? _DateTimeValue;
    /// <summary>
    /// Value
    /// </summary>
    public DateTime? DateTimeValue {
        get { return _DateTimeValue; }
        set { _DateTimeValue = value; }
    }

    // Xml Serialization Infrastructure
    void IXmlSerializable.WriteXml(XmlWriter writer) {
        if (DateTimeValue == null) {
            writer.WriteString(String.Empty);
        } else {
            writer.WriteString(DateTimeValue.Value.ToString("yyyy-MM-dd"));
            //writer.WriteString(SerializeObject.SerializeInternal(DateTimeValue.Value));
        }
    }

    void IXmlSerializable.ReadXml(XmlReader reader) {
        reader.ReadStartElement();
        String ltValue = reader.ReadString();
        reader.ReadEndElement();
        if (ltValue.Length == 0) {
            DateTimeValue = null;
        } else {                
            //Solo se admite yyyyMMdd
            //DateTimeValue = (DateTime)SerializeObject.Deserialize(typeof(DateTime), ltValue);
            DateTimeValue = new DateTime(Int32.Parse(ltValue.Substring(0, 4)),
                                Int32.Parse(ltValue.Substring(5, 2)),
                                Int32.Parse(ltValue.Substring(8, 2)));                                    
        }
    }

    XmlSchema IXmlSerializable.GetSchema() {
        return (null);
    }
}
#endregion
Rodrigo Perez Burgues