Discussion SerializeReference's code maintenance

Hello,

In my current project, SerializeReference attribute is an important feature, it's used to expose properties of different kinds of a character, and I can easily modify each property in the inspector.

But recently, I've just realized that the feature is very fragile, hence so hard sometimes to maintain the code. There are 2 main issues I've had so far:

1. When I change the name of the serialized (non-Mono) class, then the item which is an instance of that class will disappear, and I have no idea to restore it rather than re-add it manually.

2. When I add a new serialized field to the serialized class, all the referenced instances of that class will disappear as well.

(In both cases, there are red error messages in the console, I don't remember exactly but they were kind of "class not found" and "a serialized property missing" (???).

So, I open this topic in hope that other dev will share their use-cases of SerializeReference, how to make it maintainable. And specifically, to see if anyone can solve the issues I mentioned above, because it's very likely I'll have to perform the same things again when I do code-refactoring.

Thank you,

 

With respect to this, there is an undocumented attribute called:

UnityEngine.Scripting.APIUpdating.MovedFromAttribute

that solves this problem.

I've never experienced this. What version of Unity are you on? I believe in 2021 the stability of SerializeReference got improved a good amount.

 

Thank you so much for this. Too bad it is undocumented, had to figure out how the syntax should be, but it worked!

It's weird that I couldn't reproduce the error. I will update this thread if it ever occurs again.

 

After some thinking it might've been when you have a type with no serialised fields, and then introduce one later, does it have issues. Not sure if that was resolved; but I'll test later.

 

That's how I had the issue, but maybe there's more to the condition, because I couldn't reproduce on a mockup script, but could reproduce on one of my working class, when I tried to add a new serialized field to a type which initially had none, and the error appear, now I can copy it: "The serialized array of [SerializeReference] objects is missing entry for Refid -2"

 

Oh, and I forgot to mention I'm using Unity 2022.1.23

 

Well, actually the mockup script does have the issue, but not very consistent. The errors only showed once (when I load the project with the scene containing the mockup objects or the first time I Play the scene). In addition to the message above there are more:
Assertion failed on expression: 'm_ReferenceIndexMap->size() == refMap.size()'
ssertion failed on expression: 'refMap.size() == m_WriteObjectAccumulator.size()'
Assertion failed on expression: 'objCnt == refs.size() || (objCnt == refs.size() - 1)'