No serializer defined for type: System.Windows.Media.Media3D.Point3D

Question

I am trying to serialize some data using protobuf net. During the serialization I am getting an error that No serialization defined for the type Point3D. I found one issue somet

Answer 1

First off, protobuf-net is not a JSON serializer. It serializes from and to "Protocol Buffers" - the binary serialization format used by Google for much of their data communications.

That being said, there are several solutions to serialize a type, using protobuf-net, that cannot be decorated with ProtoContract attributes:

1. When contained by some other type, use a proxy or "shim" property as is shown here, OR
2. Use a surrogate as is shown here, OR
3. In runtime teach the RuntimeTypeModel about all serializable fields & properties of the type as described here in the section Serializing without attributes.

For option 2, Since a Point3D is entirely defined by its X, Y and Z coordinates, it's very easy to introduce a serialization surrogate:

[ProtoContract]
struct Point3DSurrogate
{
    public Point3DSurrogate(double x, double y, double z) : this()
    {
        this.X = x;
        this.Y = y;
        this.Z = z;
    }

    [ProtoMember(1)]
    public double X { get; set; }
    [ProtoMember(2)]
    public double Y { get; set; }
    [ProtoMember(3)]
    public double Z { get; set; }

    public static implicit operator Point3D(Point3DSurrogate surrogate)
    {
        return new Point3D(surrogate.X, surrogate.Y, surrogate.Z);
    }

    public static implicit operator Point3DSurrogate(Point3D point)
    {
        return new Point3DSurrogate(point.X, point.Y, point.Z);
    }
}

And then register it with protobuf-net just once on startup like so:

ProtoBuf.Meta.RuntimeTypeModel.Default.Add(typeof(Point3D), false).SetSurrogate(typeof(Point3DSurrogate));

Alternatively, for option 3, in startup you could define a contract for Point3D like so:

ProtoBuf.Meta.RuntimeTypeModel.Default.Add(typeof(Point3D), true);
ProtoBuf.Meta.RuntimeTypeModel.Default[typeof(Point3D)].Add(1, "X").Add(2, "Y").Add(3, "Z");

(In my opinion the surrogate is clearer despite requiring more code; defining the protocol entirely in runtime seems too fiddly.)

I don't recommend option 1 since you would need to add proxy properties to all classes that use Point3D.