C# Language Binary Serialization Controlling serialization behavior with attributes
Example
If you use the [NonSerialized] attribute, then that member will always have its default value after deserialization (ex. 0 for an int, null for string, false for a bool, etc.), regardless of any initialization done in the object itself (constructors, declarations, etc.). To compensate, the attributes [OnDeserializing] (called just BEFORE deserializing) and [OnDeserialized] (called just AFTER deserializing) together with their counterparts, [OnSerializing] and [OnSerialized] are provided.
Assume we want to add a "Rating" to our Vector and we want to make sure the value always starts at 1. The way it is written below, it will be 0 after being deserialized:
[Serializable]
public class Vector
{
public int X;
public int Y;
public int Z;
[NonSerialized]
public decimal Rating = 1M;
public Vector()
{
Rating = 1M;
}
public Vector(decimal initialRating)
{
Rating = initialRating;
}
}
To fix this problem, we can simply add the following method inside of the class to set it to 1:
[OnDeserializing]
void OnDeserializing(StreamingContext context)
{
Rating = 1M;
}
Or, if we want to set it to a calculated value, we can wait for it to be finished deserializing and then set it:
[OnDeserialized]
void OnDeserialized(StreamingContext context)
{
Rating = 1 + ((X+Y+Z)/3);
}
Similarly, we can control how things are written out by using [OnSerializing] and [OnSerialized].
