C# OptionalField default value

Question

Keep in mind this is an Older version of .net 2.0 - 2.5 because i'm using Unity 5.6.2f1

[System.Serializable]
public class SaveManager {

    [OptionalField]
    public float version = 1.5f;
    [OptionalField]
    public string versionString = "1.5";
}

When using the above class to save data to a text file by using BinaryFormatter, these values will be set to defaults. version will be 0 versionString will be ""

Is there any way to have nonexisting optional fields have default values? I have been googling this issue for a while but I haven't found any useful information.

To clarify, this issue is reproduced by Serializing SaveManager class with no fields inside of it, saving the data to a txt file. Then update the SaveManager class to include the OptionalField float version, and then trying to read the saved data, and then deserialize it back into SaveManager.

Answer 1

Update: I made a gist following this article , but using your class. I serialize and deserialize the file and the initial value of 1.5 remains

Answer 2

[System.Serializable]
public class SaveManager {

    [OnDeserializing()]
    internal void OnDeserializingMethod(StreamingContext context) {
        version = 1.5f;
        resolutionSetting = 1;
        notificationTimer = 5 * 60;
        hideNameTagTimer = 0 * 60;
        storedLevelName = "little_transparent";
        fartVolume = 0f;
        fartToggle = true;
        nametagsCollideWithCharacters = true;
    }

    [OptionalField]
    public float version = 1.5f;

Fixed by using OnDeserializing() Thanks for everyone that tried to help me!