Question Dropdown Attribute does not trigger OnValidate

I'm using a small asset from the unity asset store:
https://assetstore.unity.com/packages/tools/utilities/dropdown-attribute-180951

In general, it works as expected, but it does not trigger OnValidate when the field where it is placed changes.

Code (CSharp):

1. [CreateAssetMenu(fileName = "Types")]
2. public class Types : ScriptableObject
3. {
4.     public List<string> TypeNames;
5. }

Code (CSharp):

1. [CreateAssetMenu (fileName = "Data")]
2. public class Data : ScriptableObject
3. {
4.     [SerializeField]
5.     private Types _types;
6.     [Dropdown("_types.TypeNames")]
7.     public string Type;
8.  
9.     private void OnValidate()
10.     {
11.         Debug.Log(Type);
12.     }
13. }

The Dropdown Attribute itself is inherited from PropertyAttribute and has a CustomPropertyDrawer

How can I make some logic work in an object if a field marked with Dropdown Attribute changes?

 

I'm guessing it uses reflection to change the field and thus it won't trigger OnValidate. You could add that to the script though: if the value did change just call OnValidate manually on the target script.

 

I don't really need OnValidate, I just wanted to run additional logic when the value changes. But the value changes so that even OnValidate is not called.

In the attribute itself, I found only constructors and they are triggered only when a window opens with a field marked with this attribute.

Code (CSharp):

1. public class DropdownAttribute : PropertyAttribute
2. {
3.     public Type Type = null;
4.     public string ListPath = "";
5.     public string ItemNameProperty = "";
6.     public List<Object> List = new List<Object>();
7.     public int SelectedID = -1;
8.     public GetItemNameCallback GetItemName = null;
9.     public DropdownAttribute(string listPath, string ItemNameProperty)
10.     {//With property name to get name
11.         //[Dropdown("SkillDatabase.Instance.SkillList", "skillID")]
12.         ListPath = listPath;
13.         GetItemName = ( (baseMaster, obj) =>
14.          {
15.              return ReflectionSystem.GetValue(baseMaster, obj, ItemNameProperty)?.ToString();
16.          });
17.         this.ItemNameProperty = ItemNameProperty;
18.     }
19.     public DropdownAttribute(string listPath)
20.     {
21.         ListPath = listPath;
22.         GetItemName = ((baseMaster, master) =>
23.         {
24.             if(master is Object)
25.             {//is Unity Object
26.                 return master.GetType().GetProperty("name").GetValue(master).ToString();
27.             }
28.             else if(master is string)
29.             {//string
30.                 return master.ToString();
31.             }
32.             else if(master.GetType().IsPrimitive)
33.             {//short, long, int, bool, char, double, float
34.                 return master.ToString();
35.             }
36.             else
37.             {//object
38.                 return JsonUtility.ToJson(master);
39.             }
40.         });
41.     }
42. }

PropertyDrawer is very large and I didn’t really understand it.

How do I call some logic on the target ScriptableObject when the value of a field with this attribute changes? Should I search in PropertyDrawer?