Controlling serialization behavior with attributes
suggest changeIf 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]
.