Why does SerializationInfo not have TryGetValue methods?

Question

When implementing the ISerializable interface in C#, we provide a constructor which takes a SerializationInfo object, and then queries it with various

Answer 1

Well no one answered 'why', but I'm guessing that's addressed to MS..

My implementation for anyone in need:

public static class SerializationInfoExtensions
{
    public static bool TryGetValue<T>(this SerializationInfo serializationInfo, string name, out T value)
    {
        try
        {
            value = (T) serializationInfo.GetValue(name, typeof(T));
            return true;
        }
        catch (SerializationException)
        {
            value = default(T);
            return false;
        }
    }

    public static T GetValueOrDefault<T>(this SerializationInfo serializationInfo, string name, Lazy<T> defaultValue)
    {
        try
        {
            return (T) serializationInfo.GetValue(name, typeof(T));
        }
        catch (SerializationException)
        {
            return defaultValue.Value;
        }
    }
}

Answer 2

In addition to the enumerating solution, there is an internal method SerializationInfo.GetValueNoThrow() according to the Reference Source.

You can e.g. make an extension method like this and avoid the exception overhead:

static class SerializationInfoExtensions
{
    private static MethodInfo _GetValueNoThrow =
        typeof(SerializationInfo).GetMethod("GetValueNoThrow",
                                            BindingFlags.Instance | BindingFlags.NonPublic);

    public static Object GetOptValue(this SerializationInfo info, String name, Type type)
    {
        return _GetValueNoThrow.Invoke(info, new object[] { name, type });
    }
}

Answer 3

You can iterate over the available fields and use switch, though...

foreach(SerializationEntry entry in info) {
    switch(entry.Name) {
        ...
    }
}

Or you could use protobuf-net ;-p