Xml Serialization of ReadOnlyCollections

Question

I have some container classes that expose their collections through a ReadOnlyCollection. Custom Methods are provided to Add and Remove from the collection which also perform some custom logic.

For example:

public class Foo
{
    List<Bar> _barList = new List<Bar>();

    public ReadOnlyCollection<Bar> BarList
    {
        get { return _barList.AsReadOnly(); }
    }

    public void AddBar(Bar bar)
    {
        if (bar.Value > 10)
            _barList.Add(bar);
        else
            MessageBox.Show("Cannot add to Foo. The value of Bar is too high");
    }
    public void RemoveBar(Bar bar)
    {
        _barList.Remove(bar);
        // Foo.DoSomeOtherStuff();
    }

}

public class Bar
{
    public string Name { get; set; }
    public int Value { get; set; }
}

This is all well and good but when i come to serialise Foo with the Xml Serializer an exception is thrown.

Can anyone offer a good way of going about this?

Thanks

Answer 1

Indeed, that won't work. So don't do that. Additionally, there are no hooks to detect xml serialization except the oh-so-painful IXmlSerializable.

So either:

• don't use a read-only collection here
• implement IXmlSerializable (tricky)
• have a dual API (one read-only, one not; serialize the "not" - tricky as XmlSerializer only handles publicx members)
• use a separate DTO for serialization