C# Serialization Issue

Question

I'm having some trouble with binary serialization in C#... I should add that I'm a relative noob with C#, so please explain in simple terms :)

Anyway, I have this class (truncated for clarity):

[Serializable]
public class Player : Ship {

And Ship looks like this (again, truncated):

[Serializable]
public class Ship : TiledActor {
    public float MaxUserTurnPerSecond;
    public float RemainingShieldStrength;
    public float MaxShieldStrength;
    public float ShieldRechargeRate;
    public float ShieldRechargeDelay;
    public Color ShieldColor;
    public float ThrusterAccelerationScale;
    public Color RippleTrailColor;
    public float MinimumRippleSpeed;
    public float MaxEnergy;
    public float CurrentEnergy;
    public float EnergyRechargeRate;
    public float MaxSecondaryAmmoCapacity;
    public int CurrentSecondaryAmmoCount;
    public Weapon PrimaryWeapon;
    public Weapon SecondaryWeapon;
    protected ShieldActor ShieldTex;

    [NonSerialized]
    public MoXNA.ParticleMachines.PM_Explosion_Particle_Count ExplosionSize;
    [NonSerialized]
    protected MoXNA.ParticleMachines.MinSpeedRippleTrail rippleTrail;

    /* ... Truncated here */

So, as you can see, I wish to serialize the Player class. However, when I try this, I get this error:

An unhandled exception of type 'System.Runtime.Serialization.SerializationException' occurred in mscorlib.dll

Additional information: Type 'MoXNA.ParticleMachines.MinSpeedRippleTrail' in Assembly 'SpaceshipInABox, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.

The odd thing here is that I marked rippleTrail (which is the MinSpeedRippleTrail object) as [NonSerialized]... I don't want to serialize it (it's just a visual effect).

I used "Find all references" and that's the only MinSpeedRippleTrail object in the entire program, so what the hell?

Thanks.

Can you show the code where this error is thrown? Which data you are trying to write and what not. — Spidy
I don't see why this doesn't work, but you can give the following a try. Try adding Serializable to the MinSpeedRippleTrail class/struct anyhow, perhaps even though the NonSerialized attribute is applied, it still checks first whether it can be serialized? — Steven Jeuris
There's no decent explanation for this. Only a crummy one, your program is loading an old version of the assembly. Fuslogvw.exe and log all binds to double-check this. Also watch out for deserializing old data. — Hans Passant

Marc Gravell Marc Gravell · Accepted Answer · 2011-02-25T18:55:05

The usual problem here is an event. BinaryFormatter includes events, which many people don't expect. The event field must be marked, for example:

[field:NonSerialized]
public event EventHandler Foo;

It is painfully easy to get an event subscription that you didn't anticipate break the serializer (a capture class, perhaps).

However, I also encourage you:

don't use public fields; use properties
don't use BinaryFormatter - it bites most people eventually; and bites hard

If you want a binary serializer that works with XNA, consider protobuf-net; it is faster, has smaller output, adapts to change more gracefully ... and is free. Caveat: I wrote it.

C# Serialization Issue

2 Answers