C# – Store Dictionary in application settings

.net-3.5cdictionarysettings

I have a dictionary of strings that i want the user to be able to add/remove info from then store it for them so it they can access it the next time the program restarts

I am unclear on how i can store a dictionary as a setting. I see that under system.collections.special there is a thing called a stringdictionary but ive read that SD are outdated and shouldn't be used.

also in the future i may have need to store a dictionary that is not strings only (int string)

how would you store a dictionary in the settings file for a .net application?

Best Answer

You can use this class derived from StringDictionary. To be useful for application settings it implements IXmlSerializable. Or you can use similar approach to implement your own XmlSerializable class.

public class SerializableStringDictionary : System.Collections.Specialized.StringDictionary, System.Xml.Serialization.IXmlSerializable
{
    public System.Xml.Schema.XmlSchema GetSchema()
    {
        return null;
    }

    public void ReadXml(System.Xml.XmlReader reader)
    {
        while (reader.Read() &&
            !(reader.NodeType == System.Xml.XmlNodeType.EndElement && reader.LocalName == this.GetType().Name))
        {
            var name = reader["Name"];
            if (name == null)
                throw new FormatException();

            var value = reader["Value"];
            this[name] = value;
        }
    }

    public void WriteXml(System.Xml.XmlWriter writer)
    {
        foreach (System.Collections.DictionaryEntry entry in this)
        {
            writer.WriteStartElement("Pair");
            writer.WriteAttributeString("Name", (string)entry.Key);
            writer.WriteAttributeString("Value", (string)entry.Value);
            writer.WriteEndElement();
        }
    }
}

Resulting XML fragment will look similar to:

...
<setting name="PluginSettings" serializeAs="Xml">
    <value>
        <SerializableStringDictionary>
            <Pair Name="property1" Value="True" />
            <Pair Name="property2" Value="05/01/2011 0:00:00" />
        </SerializableStringDictionary>
    </value>
</setting>
...
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