There was an error reflecting type - XML Serialization issue

Question

I have a Dictionary object which needs to be written into an XML file. The dictionary contains String type as Key and a custom class\'s Object (Deriving from System.Windows.

Answer 1

I used DataContractSerializer from System.Runtime.Serialization.dll. Serialized/deserialized my class with two Dictionary properties without any questions.

Answer 2

Guys.. With a little help on web I found a solution..

I had to add another class

[XmlRoot("dictionary")]
public class SerializableDictionary<TKey, TValue>: Dictionary<TKey, TValue>, IXmlSerializable
{      

    #region IXmlSerializable Members
    public System.Xml.Schema.XmlSchema GetSchema()
    {
        return null;
    }


    public void ReadXml(System.Xml.XmlReader reader)
    {
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue)); 

        bool wasEmpty = reader.IsEmptyElement;
        reader.Read(); 

        if (wasEmpty)
            return; 

        while (reader.NodeType != System.Xml.XmlNodeType.EndElement)
        {
            reader.ReadStartElement("item");
            reader.ReadStartElement("key");
            TKey key = (TKey)keySerializer.Deserialize(reader);
            reader.ReadEndElement();
            reader.ReadStartElement("value");
            TValue value = (TValue)valueSerializer.Deserialize(reader);
            reader.ReadEndElement();
            this.Add(key, value);
            reader.ReadEndElement();
            reader.MoveToContent();
        }

        reader.ReadEndElement();
    }



    public void WriteXml(System.Xml.XmlWriter writer)
    {
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue)); 

        foreach (TKey key in this.Keys)
        {
            writer.WriteStartElement("item");
            writer.WriteStartElement("key");
            keySerializer.Serialize(writer, key);
            writer.WriteEndElement();
            writer.WriteStartElement("value");
            TValue value = this[key];
            valueSerializer.Serialize(writer, value);
            writer.WriteEndElement();
            writer.WriteEndElement();
        }

    }

    #endregion

}

Then used the SerializableDictionary object instead of normal Dictionary. Also in my CommonControls class I had to implement "IXmlSerializable" with following methods.

 #region IXmlSerializable Members

    public System.Xml.Schema.XmlSchema GetSchema()
    {
        throw new NotImplementedException();
    }

    public void ReadXml(XmlReader reader)
    {
        throw new NotImplementedException();
    }

    public void WriteXml(XmlWriter writer)
    {
        throw new NotImplementedException();
    }

    #endregion

Now the whole thing is working ok. Thanks Everyone. !!!

Answer 3

I think you'll find that Dictionary cannot be serialized with XmlSerializer

Answer 4

Generic dictionaries cannot be XmlSerialized. The error you get is caused by the public property DicCtrl.

• Use the [XmlIgnore] attribute to skip this property when serializing (which is probably not what you want).
• Change the type of the property to a type that can be serialized e.g. List<T>
• Find or implement a serializable dictionary
• Or implement IXmlSerializable

BTW the [Serializable] attribute is only needed for binary serialization. You do not need it for Xml serialization.