Is there a serializable generic Key/Value pair class in .NET?

Question

I\'m looking for a key/value pair object that I can include in a web service.

I tried using .NET\'s System.Collections.Generic.KeyValuePair<> class, but it doe

Answer 1

I don't think there is as Dictionary<> itself isn't XML serializable, when I had need to send a dictionary object via a web service I ended up wrapping the Dictionary<> object myself and adding support for IXMLSerializable.

/// <summary>
/// Represents an XML serializable collection of keys and values.
/// </summary>
/// <typeparam name="TKey">The type of the keys in the dictionary.</typeparam>
/// <typeparam name="TValue">The type of the values in the dictionary.</typeparam>
[XmlRoot("dictionary")]
public class SerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, IXmlSerializable
{
    #region Constants

    /// <summary>
    /// The default XML tag name for an item.
    /// </summary>
    private const string DEFAULT_ITEM_TAG = "Item";

    /// <summary>
    /// The default XML tag name for a key.
    /// </summary>
    private const string DEFAULT_KEY_TAG = "Key";

    /// <summary>
    /// The default XML tag name for a value.
    /// </summary>
    private const string DEFAULT_VALUE_TAG = "Value";

    #endregion

    #region Protected Properties

    /// <summary>
    /// Gets the XML tag name for an item.
    /// </summary>
    protected virtual string ItemTagName
    {
        get
        {
            return DEFAULT_ITEM_TAG;
        }
    }

    /// <summary>
    /// Gets the XML tag name for a key.
    /// </summary>
    protected virtual string KeyTagName
    {
        get
        {
            return DEFAULT_KEY_TAG;
        }
    }

    /// <summary>
    /// Gets the XML tag name for a value.
    /// </summary>
    protected virtual string ValueTagName
    {
        get
        {
            return DEFAULT_VALUE_TAG;
        }
    }

    #endregion

    #region Public Methods

    /// <summary>
    /// Gets the XML schema for the XML serialization.
    /// </summary>
    /// <returns>An XML schema for the serialized object.</returns>
    public XmlSchema GetSchema()
    {
        return null;
    }

    /// <summary>
    /// Deserializes the object from XML.
    /// </summary>
    /// <param name="reader">The XML representation of the object.</param>
    public void ReadXml(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 != XmlNodeType.EndElement)
        {
            reader.ReadStartElement(ItemTagName);

            reader.ReadStartElement(KeyTagName);
            TKey key = (TKey)keySerializer.Deserialize(reader);
            reader.ReadEndElement();

            reader.ReadStartElement(ValueTagName);
            TValue value = (TValue)valueSerializer.Deserialize(reader);
            reader.ReadEndElement();

            this.Add(key, value);

            reader.ReadEndElement();
            reader.MoveToContent();
        }

        reader.ReadEndElement();
    }

    /// <summary>
    /// Serializes this instance to XML.
    /// </summary>
    /// <param name="writer">The writer to serialize to.</param>
    public void WriteXml(XmlWriter writer)
    {
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

        foreach (TKey key in this.Keys)
        {
            writer.WriteStartElement(ItemTagName);

            writer.WriteStartElement(KeyTagName);
            keySerializer.Serialize(writer, key);
            writer.WriteEndElement();

            writer.WriteStartElement(ValueTagName);
            TValue value = this[key];
            valueSerializer.Serialize(writer, value);
            writer.WriteEndElement();

            writer.WriteEndElement();
        }
    }

    #endregion
}

Answer 2

DataTable is my favorite collection for (solely) wrapping data to be serialized to JSON, since it's easy to expand without the need for an extra struct & acts like a serializable replacement for Tuple<>[]

Maybe not the cleanest way, but I prefer to include & use it directly in the classes (which shall be serialized), instead of declaring a new struct

class AnyClassToBeSerialized
{
    public DataTable KeyValuePairs { get; }

    public AnyClassToBeSerialized
    {
        KeyValuePairs = new DataTable();
        KeyValuePairs.Columns.Add("Key", typeof(string));
        KeyValuePairs.Columns.Add("Value", typeof(string));
    }

    public void AddEntry(string key, string value)
    {
        DataRow row = KeyValuePairs.NewRow();
        row["Key"] = key; // "Key" & "Value" used only for example
        row["Value"] = value;
        KeyValuePairs.Rows.Add(row);
    }
}

Answer 3

You can use Tuple<string,object>

see this for more details on Tuple usage : Working with Tuple in C# 4.0

Answer 4

In the 4.0 Framework, there is also the addition of the Tuple family of classes that are serializable and equatable. You can use Tuple.Create(a, b) or new Tuple<T1, T2>(a, b).