Showcase Sub class property drawer

Hello,

I made a custom property drawer that lets you change a polymorphic class in editor & thought I'd share as I couldnt find it anywhere else.

To use it the base class & all classes you want to set it to must set as serializable.
Then when declaring the variable add the attributes [SerializeReference, Subclass], SerializeReference is needed as otherwise Unity wont serialize your class properly!

This was tested on Unity 2021.3.1f, it may work on older versions but that is untested.

It can be used on a single variable:

Code (CSharp):

1. [SerializeReference, Subclass]
2. public TargetComparer Comparer;

Also works with arrays & lists:

Code (CSharp):

1. [SerializeReference, Subclass]
2. public InteractFilter[] Filter;
3.  
4. [SerializeReference, Subclass(IsList=true)]
5. public List<InteractFilter> Filter;

To use this your class layout should look something like this:

Code (CSharp):

1. [System.Serializable]
2. public class BaseClass
3. {
4. };
5.  
6. [System.Serializable]
7. public class ClassA : BaseClass
8. {
9.      public int TestInt;
10. };
11.  
12. [System.Serializable]
13. public class ClassB : BaseClass
14. {
15.     public float TestFloat
16. };

It can also be used with inherited templated classes but the type needs to be defined already:

Code (CSharp):

1. [System.Serializable]
2. public class BaseClass
3. {
4. };
5.  
6. [System.Serializable]
7. public class BaseClass<T> : BaseClass
8. {
9.      public T MyVar;
10. };
11.  
12. [System.Serializable]
13. public class ClassA : BaseClass<int>
14. {
15. };
16.  
17. [System.Serializable]
18. public class ClassB : BaseClass<float>
19. {
20. };

It also works with deeper classes:

Code (CSharp):

1. [System.Serializable]
2. public class BaseClass
3. {
4. };
5.  
6. [System.Serializable]
7. public class ClassA : BaseClass
8. {
9.      public int TestInt;
10. };
11.  
12. [System.Serializable]
13. public class ClassB : ClassA
14. {
15.     public float TestFloat
16. };

Download link for unity package, its just 3 files (PropertyAttribute, PropertyDrawer, SubclassSelector)
https://github.com/lordconstant/SubclassPropertyDrawer

Any questions feel free to ask.

Cheers,
Chris

 

i literally posted a thread asking for something like this 10 minutes after you did lol

doesnt work in 2020 bc the managedReferenceValue doesnt have a getter, but i upgraded to 2021 LTS and it works just fine!

thanks for this and thanks to @spiney199 for suggesting it to me!

 

That makes sense, the property drawer is fully dependent on the new managed reference stuff.
For older projects you can just use the SubclassSelector class as that handles finding the subclasses & drawing the dropdown, then you can create a custom editor for your class. Its just move convenient as a property drawer

 

there's some incompatibility with Editor attribute drawers, such as [TextArea]. ive posted an issue on your github