Serialize XML array of unknown element name

Question

I have a problem with deserialization of a not so common XML structure. Unfortunately I have no influence on the source site.

The XML has a root named Bus that can have multiple Device elements. The Device element can have multiple values. (so long so good).

<Bus protocol="Meterbus" baud="2400">
    <Device Name="DHZ-1" PrimaryAddr="62">
        <Energie _="value" Name="Energie" size="13"/>
        <Spannung _="value" Name="Spannung" size="13"/>
        <Strom _="value" Name="Strom" size="13"/>
        <Leistung _="value" Name="Leistung" size="13"/>
        <Seriennummer _="value" Name="Seriennummer" size="13"/>
        <... _="..." Name="..." size=".."/>
    </Device>
</Bus>

The problem is that the values have complete dynamic element names, but same parameter.

It can be something like <somename _="value" Name="somename" size="13"/>.

But they should all be serialized as a Value type, no matter the are named.

Something like this:

public class Value
{
    [XmlAttribute("_")]
    public String _
    {
        get;
        set;
    }

    [XmlAttribute("Name")]
    public String Name
    {
        get;
        set;
    }

    [XmlAttribute("size")]
    public String Size
    {
        get;
        set;
    }
}

The Device class looks like this:

public class Device
{
    [XmlAttribute("Name")]
    public String Name
    {
        get;
        set;
    }

    [XmlAttribute("PrimaryAddr")]
    public String PrimaryAddr
    {
        get;
        set;
    }

    [???]
    public Array<Value> Values
    {
        get;
        set;
    }
}

How can I explain this to the serializer?

Steffen Mangold · Accepted Answer · 2017-12-11 04:12:21Z

The XmlSerializer class implements an UnknownElement event which is invoked whenever an undefined/unknown element is being parser. You can subscribe an handler to this event and deserialize the undefined/unknown elements manually:

XmlSerializer serializer = new XmlSerializer(typeof(Bus));
serializer.UnknownElement += new XmlElementEventHandler(Serializer_UnknownElement);

A worked example:

private void Serializer_UnknownElement(Object sender, XmlElementEventArgs e)
{
    var device = e.ObjectBeingDeserialized as Device;

    if (device != null)
    {
        XmlElement element = e.Element;  

        using (StringReader reader = new StringReader(element.OuterXml))
        {
            XmlSerializer valueSerializer = new XmlSerializer(typeof(Value), (new XmlRootAttribute(element.Name)));

            Value value = (Value)valueSerializer.Deserialize(reader);
            value.Name = element.Name; // implement it so you can rebuild the tag back

            device.Values.Add(value);
        }
    }
}

Official MSDN documentation here.

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